According to your User Agent you are running Firefox 3.5, is that true? If so, please update to Firefox 17. Update Firefox to the latest release

If you are still seeing the issue, I'd be interested in a few things:

1. Type about:support into your address bar, press Enter. Copy and paste the information found there to this thread.
2. Try to disable Hardware Acceleration. Turning off hardware acceleration

The whole problem centered on my recent upgrade to 17.0, so this "User Agent" you mention is incorrect.

Your system is complaining that my post is too long with the "about:support" information so I will post in pieces.

<Please keep the length of your content to 10,000 characters or less. It is currently 19,196 characters.>

= start about:support ====

 Application Basics

       Name
       Firefox

       Version
       17.0

       User Agent
       Mozilla/5.0 (Windows; U; Windows NT 5.1; en-US; rv:1.9.1.5) Gecko/20091102 Firefox/3.5.5

       Profile Folder

         Show Folder

       Enabled Plugins

         about:plugins

       Build Configuration

         about:buildconfig

       Crash Reports

         about:crashes

       Memory Use

         about:memory

 Extensions

       Name

       Version

       Enabled

       ID

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       0.23
       true
       {8b86149f-01fb-4842-9dd8-4d7eb02fd055}

       Garmin Communicator
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       {195A3098-0BD5-4e90-AE22-BA1C540AFD1E}

       iMacros for Firefox
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       true
       {81BF1D23-5F17-408D-AC6B-BD6DF7CAF670}

       LogMeIn, Inc. Remote Access Plugin
       1.0.0.664
       false
       LogMeInClient@logmein.com

       ScrapBook Plus
       1.8.22.38
       false
       scrapbookplus@addons.mozilla.org

 Important Modified Preferences

     Name

     Value

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       0

       accessibility.warn_on_browsewithcaret
       false

       browser.cache.disk.capacity
       1048576

       browser.cache.disk.smart_size.enabled
       false

       browser.cache.disk.smart_size.first_run
       false

       browser.cache.disk.smart_size_cached_value
       829440

       browser.history_expire_days.mirror
       20

       browser.history_expire_days_min
       120

       browser.link.open_newwindow.restriction
       0

       browser.places.importDefaults
       false

       browser.places.migratePostDataAnnotations
       false

       browser.places.smartBookmarksVersion
       4

       browser.places.updateRecentTagsUri
       false

       browser.search.update
       false

       browser.search.useDBForOrder
       true

       browser.startup.homepage
       about:blank

       browser.startup.homepage_override.buildID
       20121119183901

       browser.startup.homepage_override.mstone
       17.0

       browser.tabs.loadInBackground
       false

       browser.tabs.onTop
       false

       browser.tabs.warnOnClose
       false

       browser.tabs.warnOnOpen
       false

       dom.ipc.plugins.enabled
       false

       extensions.lastAppVersion
       17.0

       general.autoScroll
       false

       general.useragent.extra.microsoftdotnet
       ( .NET CLR 3.5.30729; .NET4.0C)

       general.useragent.override
       Mozilla/5.0 (Windows; U; Windows NT 5.1; en-US; rv:1.9.1.5) Gecko/20091102 Firefox/3.5.5

       gfx.direct3d.prefer_10_1
       true

       network.cookie.blockFutureCookies
       true

       network.cookie.prefsMigrated
       true

       places.database.lastMaintenance
       1352657501

       places.history.expiration.transient_current_max_pages
       104858

       places.history.expiration.transient_optimal_database_size
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       places.last_vacuum
       1304275207

       print.print_printer
       Canon MP530 Series Printer

       print.printer_Canon_Inkjet_MP530_Series.print_bgcolor
       false

       print.printer_Canon_Inkjet_MP530_Series.print_bgimages
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       print.printer_Canon_Inkjet_MP530_Series.print_command

       print.printer_Canon_Inkjet_MP530_Series.print_downloadfonts
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       print.printer_Canon_Inkjet_MP530_Series.print_edge_bottom
       0

       print.printer_Canon_Inkjet_MP530_Series.print_edge_left
       0

       print.printer_Canon_Inkjet_MP530_Series.print_edge_right
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       print.printer_Canon_Inkjet_MP530_Series.print_edge_top
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       print.printer_Canon_Inkjet_MP530_Series.print_evenpages
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       print.printer_Canon_Inkjet_MP530_Series.print_footercenter

       print.printer_Canon_Inkjet_MP530_Series.print_footerleft
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       print.printer_Canon_Inkjet_MP530_Series.print_footerright
       &D

       print.printer_Canon_Inkjet_MP530_Series.print_headercenter

       print.printer_Canon_Inkjet_MP530_Series.print_headerleft
       &T

       print.printer_Canon_Inkjet_MP530_Series.print_headerright
       &U

       print.printer_Canon_Inkjet_MP530_Series.print_in_color
       true

       print.printer_Canon_Inkjet_MP530_Series.print_margin_bottom
       0.5

       print.printer_Canon_Inkjet_MP530_Series.print_margin_left
       0.5

       print.printer_Canon_Inkjet_MP530_Series.print_margin_right
       0.5

       print.printer_Canon_Inkjet_MP530_Series.print_margin_top
       0.5

       print.printer_Canon_Inkjet_MP530_Series.print_oddpages
       true

       print.printer_Canon_Inkjet_MP530_Series.print_orientation
       0

       print.printer_Canon_Inkjet_MP530_Series.print_pagedelay
       500

       print.printer_Canon_Inkjet_MP530_Series.print_paper_data
       1

       print.printer_Canon_Inkjet_MP530_Series.print_paper_height
       11.00

       print.printer_Canon_Inkjet_MP530_Series.print_paper_size_type
       0

       print.printer_Canon_Inkjet_MP530_Series.print_paper_size_unit
       0

       print.printer_Canon_Inkjet_MP530_Series.print_paper_width
       8.50

       print.printer_Canon_Inkjet_MP530_Series.print_reversed
       false

       print.printer_Canon_Inkjet_MP530_Series.print_scaling
       1.00

       print.printer_Canon_Inkjet_MP530_Series.print_shrink_to_fit
       true

       print.printer_Canon_Inkjet_MP530_Series.print_to_file
       false

       print.printer_Canon_Inkjet_MP530_Series.print_unwriteable_margin_bottom
       0

       print.printer_Canon_Inkjet_MP530_Series.print_unwriteable_margin_left
       0

       print.printer_Canon_Inkjet_MP530_Series.print_unwriteable_margin_right
       0

print.printer_Canon_Inkjet_MP530_Series.print_unwriteable_margin_right

       0

       print.printer_Canon_Inkjet_MP530_Series.print_unwriteable_margin_top
       0

       print.printer_Canon_MP530_Series_Printer.print_bgcolor
       false

       print.printer_Canon_MP530_Series_Printer.print_bgimages
       false

       print.printer_Canon_MP530_Series_Printer.print_command

       print.printer_Canon_MP530_Series_Printer.print_downloadfonts
       true

       print.printer_Canon_MP530_Series_Printer.print_edge_bottom
       0

       print.printer_Canon_MP530_Series_Printer.print_edge_left
       0

       print.printer_Canon_MP530_Series_Printer.print_edge_right
       0

       print.printer_Canon_MP530_Series_Printer.print_edge_top
       0

       print.printer_Canon_MP530_Series_Printer.print_evenpages
       true

       print.printer_Canon_MP530_Series_Printer.print_footercenter

       print.printer_Canon_MP530_Series_Printer.print_footerleft

       print.printer_Canon_MP530_Series_Printer.print_footerright

       print.printer_Canon_MP530_Series_Printer.print_headercenter

       print.printer_Canon_MP530_Series_Printer.print_headerleft

       print.printer_Canon_MP530_Series_Printer.print_headerright

       print.printer_Canon_MP530_Series_Printer.print_in_color
       true

       print.printer_Canon_MP530_Series_Printer.print_margin_bottom
       0

       print.printer_Canon_MP530_Series_Printer.print_margin_left
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       print.printer_Canon_MP530_Series_Printer.print_margin_right
       0

       print.printer_Canon_MP530_Series_Printer.print_margin_top
       0

       print.printer_Canon_MP530_Series_Printer.print_oddpages
       true

       print.printer_Canon_MP530_Series_Printer.print_orientation
       0

       print.printer_Canon_MP530_Series_Printer.print_page_delay
       50

       print.printer_Canon_MP530_Series_Printer.print_pagedelay
       500

       print.printer_Canon_MP530_Series_Printer.print_paper_data
       1

       print.printer_Canon_MP530_Series_Printer.print_paper_height
       11.00

       print.printer_Canon_MP530_Series_Printer.print_paper_size
       0

       print.printer_Canon_MP530_Series_Printer.print_paper_size_type
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       print.printer_Canon_MP530_Series_Printer.print_paper_size_unit
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       print.printer_Canon_MP530_Series_Printer.print_paper_width
       8.50

       print.printer_Canon_MP530_Series_Printer.print_reversed
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       print.printer_Canon_MP530_Series_Printer.print_scaling
       1.00

       print.printer_Canon_MP530_Series_Printer.print_shrink_to_fit
       true

       print.printer_Canon_MP530_Series_Printer.print_to_file
       false

       print.printer_Canon_MP530_Series_Printer.print_unwriteable_margin_bottom
       0

       print.printer_Canon_MP530_Series_Printer.print_unwriteable_margin_left
       0

       print.printer_Canon_MP530_Series_Printer.print_unwriteable_margin_right
       0

       print.printer_Canon_MP530_Series_Printer.print_unwriteable_margin_top
       0

       print.printer_Canon_i9900.print_bgcolor
       false

       print.printer_Canon_i9900.print_bgimages
       false

       print.printer_Canon_i9900.print_command

       print.printer_Canon_i9900.print_downloadfonts
       true

       print.printer_Canon_i9900.print_edge_bottom
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       print.printer_Canon_i9900.print_edge_left
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       print.printer_Canon_i9900.print_edge_right
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       print.printer_Canon_i9900.print_edge_top
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       print.printer_Canon_i9900.print_evenpages
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       print.printer_Canon_i9900.print_footercenter

       print.printer_Canon_i9900.print_footerleft

       print.printer_Canon_i9900.print_footerright

       print.printer_Canon_i9900.print_headercenter

       print.printer_Canon_i9900.print_headerleft

       print.printer_Canon_i9900.print_headerright

       print.printer_Canon_i9900.print_in_color
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       print.printer_Canon_i9900.print_margin_bottom
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       print.printer_Canon_i9900.print_margin_left
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       print.printer_Canon_i9900.print_margin_right
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       print.printer_Canon_i9900.print_margin_top
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       print.printer_Canon_i9900.print_oddpages
       true

       print.printer_Canon_i9900.print_orientation
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       print.printer_Canon_i9900.print_pagedelay
       500

       print.printer_Canon_i9900.print_paper_data
       1

       print.printer_Canon_i9900.print_paper_height
       11.00

       print.printer_Canon_i9900.print_paper_size
       0

       print.printer_Canon_i9900.print_paper_size_type
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       print.printer_Canon_i9900.print_paper_size_unit
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       print.printer_Canon_i9900.print_paper_width
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       print.printer_Canon_i9900.print_printer
       Canon i9900

       print.printer_Canon_i9900.print_reversed
       false

       print.printer_Canon_i9900.print_scaling
       1.00

       print.printer_Canon_i9900.print_shrink_to_fit
       true

       print.printer_Canon_i9900.print_to_file
       false

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       print.printer_Canon_i9900.print_unwriteable_margin_right
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       print.printer_Canon_i9900.print_unwriteable_margin_top
       0

       print.printer_HP_LaserJet_4P.print_bgcolor
       false

       print.printer_HP_LaserJet_4P.print_bgimages
       false

       print.printer_HP_LaserJet_4P.print_command

       print.printer_HP_LaserJet_4P.print_downloadfonts
       true

       print.printer_HP_LaserJet_4P.print_evenpages
       true

       print.printer_HP_LaserJet_4P.print_footercenter

       print.printer_HP_LaserJet_4P.print_footerleft

       print.printer_HP_LaserJet_4P.print_footerright

       print.printer_HP_LaserJet_4P.print_headercenter

       print.printer_HP_LaserJet_4P.print_headerleft

       print.printer_HP_LaserJet_4P.print_headerright

       print.printer_HP_LaserJet_4P.print_in_color
       true

       print.printer_HP_LaserJet_4P.print_margin_bottom
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       print.printer_HP_LaserJet_4P.print_margin_left
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       print.printer_HP_LaserJet_4P.print_margin_right
       0

       print.printer_HP_LaserJet_4P.print_margin_top
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       print.printer_HP_LaserJet_4P.print_oddpages
       true

       print.printer_HP_LaserJet_4P.print_orientation
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       print.printer_HP_LaserJet_4P.print_paper_size_type
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print.printer_HP_LaserJet_4P.print_printer

       HP LaserJet 4P

       print.printer_HP_LaserJet_4P.print_reversed
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       print.printer_HP_LaserJet_4P.print_scaling
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       print.printer_HP_LaserJet_4P.print_shrink_to_fit
       true

       print.printer_HP_LaserJet_4P.print_to_file
       false

       print.printer_Microsoft_XPS_Document_Writer.print_bgcolor
       false

       print.printer_Microsoft_XPS_Document_Writer.print_bgimages
       false

       print.printer_Microsoft_XPS_Document_Writer.print_command

       print.printer_Microsoft_XPS_Document_Writer.print_downloadfonts
       false

       print.printer_Microsoft_XPS_Document_Writer.print_edge_bottom
       0

       print.printer_Microsoft_XPS_Document_Writer.print_edge_left
       0

       print.printer_Microsoft_XPS_Document_Writer.print_edge_right
       0

       print.printer_Microsoft_XPS_Document_Writer.print_edge_top
       0

       print.printer_Microsoft_XPS_Document_Writer.print_evenpages
       true

       print.printer_Microsoft_XPS_Document_Writer.print_footercenter

       print.printer_Microsoft_XPS_Document_Writer.print_footerleft
       &PT

       print.printer_Microsoft_XPS_Document_Writer.print_footerright
       &D

       print.printer_Microsoft_XPS_Document_Writer.print_headercenter

       print.printer_Microsoft_XPS_Document_Writer.print_headerleft
       &T

       print.printer_Microsoft_XPS_Document_Writer.print_headerright
       &U

       print.printer_Microsoft_XPS_Document_Writer.print_in_color
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       print.printer_Microsoft_XPS_Document_Writer.print_margin_bottom
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       print.printer_Microsoft_XPS_Document_Writer.print_margin_left
       0.5

       print.printer_Microsoft_XPS_Document_Writer.print_margin_right
       0.5

       print.printer_Microsoft_XPS_Document_Writer.print_margin_top
       0.5

       print.printer_Microsoft_XPS_Document_Writer.print_oddpages
       true

       print.printer_Microsoft_XPS_Document_Writer.print_orientation
       0

       print.printer_Microsoft_XPS_Document_Writer.print_pagedelay
       500

       print.printer_Microsoft_XPS_Document_Writer.print_paper_data
       1

       print.printer_Microsoft_XPS_Document_Writer.print_paper_height
       11.00

       print.printer_Microsoft_XPS_Document_Writer.print_paper_size_type
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       print.printer_Microsoft_XPS_Document_Writer.print_paper_size_unit
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       print.printer_Microsoft_XPS_Document_Writer.print_paper_width
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       print.printer_Microsoft_XPS_Document_Writer.print_reversed
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       print.printer_Microsoft_XPS_Document_Writer.print_scaling
       1.00

       print.printer_Microsoft_XPS_Document_Writer.print_shrink_to_fit
       true

       print.printer_Microsoft_XPS_Document_Writer.print_to_file
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       print.printer_Microsoft_XPS_Document_Writer.print_unwriteable_margin_bottom
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       print.printer_Microsoft_XPS_Document_Writer.print_unwriteable_margin_left
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       print.printer_Microsoft_XPS_Document_Writer.print_unwriteable_margin_top
       0

       privacy.popups.showBrowserMessage
       false

       privacy.sanitize.migrateFx3Prefs
       true

       security.OCSP.URL

       security.OCSP.signingCA
       Builtin Object Token:IPS CLASE1 root

       security.warn_viewing_mixed
       false

 Graphics

       Adapter Description
       NVIDIA GeForce GTX 570

       Vendor ID
       0x10de

       Device ID
       0x1086

       Adapter RAM
       1280

       Adapter Drivers
       nvd3dumx,nvwgf2umx,nvwgf2umx nvd3dum,nvwgf2um,nvwgf2um

       Driver Version
       8.17.12.8562

       Driver Date
       10-15-2011

       Direct2D Enabled
       true

       DirectWrite Enabled
       true (6.1.7601.17789)

       ClearType Parameters
       DISPLAY1 [ Gamma: 2200 Pixel Structure: BGR ClearType Level: 50 Enhanced Contrast: 0 ] DISPLAY4 [ Gamma: 2200 Pixel Structure: RGB ClearType Level: 100 Enhanced Contrast: 50 ]

       WebGL Renderer
       Google Inc. -- ANGLE (NVIDIA GeForce GTX 570) -- OpenGL ES 2.0 (ANGLE 1.0.0.1242)

       GPU Accelerated Windows
       1/1 Direct3D 10

       AzureCanvasBackend
       direct2d

       AzureFallbackCanvasBackend
       cairo

       AzureContentBackend
       direct2d

 JavaScript

       Incremental GC
       1

 Accessibility

       Activated
       0

       Prevent Accessibility
       0

 Library Versions

       Expected minimum version

       Version in use

       NSPR
       4.9.2
       4.9.2

       NSS
       3.13.6.0 Basic ECC
       3.13.6.0 Basic ECC

       NSS Util
       3.13.6.0
       3.13.6.0

       NSS SSL
       3.13.6.0 Basic ECC
       3.13.6.0 Basic ECC

       NSS S/MIME
       3.13.6.0 Basic ECC
       3.13.6.0 Basic ECC

==== end about:support=

I opened the nVidia control panel and did not find a setting for hardware acceleration. My driver is slightly out-of-date so I will update that but am not hopeful that will correct the problem.

Ok I have two things for you to try here:

First, yes, your User Agent is corrupted it appears. Please follow the directions at How to reset the default user agent on Firefox to fix that.

After doing that, Please update your graphics driver (the version you have is old, and I'd like to see if a newer version fixes this to help narrow down the issue). Go to http://www.nvidia.com/content/global/global.php and use the graphics card auto detect to try to find a newer version.

I updated the video driver and that solved the problem. The font is back to the way it should be.

Thanks for all your help.

I restarted the computer and the same problem is back. The fonts are bold and dirty as shown in my uploaded image.

Anything else that I can try?

Try to set the Boolean gfx.direct2d.disabled pref to true on the about:config page to disable Direct2D and leave hardware acceleration otherwise enabled.

• http://kb.mozillazine.org/about:config
• https://support.mozilla.org/kb/Troubleshooting+extensions+and+themes

I set the value to true as you suggested and it did solve the problem. Hopefully, this time it will stick.

Thanks.