The Reset Firefox feature can fix many issues by restoring Firefox to its factory default state while saving your essential information. Note: This will cause you to lose any Extensions, Open websites, and some Preferences.

To Reset Firefox do the following:

1. Go to Firefox > Help > Troubleshooting Information.
2. Click the "Reset Firefox" button.
3. Firefox will close and reset. After Firefox is done, it will show a window with the information that is imported. Click Finish.
4. Firefox will open with all factory defaults applied.

Further information can be found in the Refresh Firefox - reset add-ons and settings article.

Did this fix your problems? Please report back to us!

The reset did not solve the problem.

Photo of screen attached. (sorry for poor quality)

A few other basic trouble shooting things you can try is this: Run all Windows Updates, install all needed service packs, etc.

Update your graphics driver (Firefox uses your graphics card for some rendering, and an out of date graphics card driver can cause problems. Upgrade your graphics drivers to use hardware acceleration and WebGL

Update all your plugins (Flash, Java, etc.): http://www.mozilla.org/plugincheck/.

Download and Install MalwareBytes Anti-Malware, run a full Scan. http://www.malwarebytes.org/. This helps check that there are no viruses on your computer causing issues. You can uninstall this program after you clean off any infections.

I am running on Ubuntu Linux. All applications are the latest versions released for Ubuntu. I will check the graphics driver but I believe it is up to date also. I will check the settings for hardware acceleration and WebGL. The hardware acceleration was turned on until a couple of days ago. I saw a post that suggested that the acceleration may be causing the problem so I turned it off - no change.

All plugins were purged when the reset was done. None have been reloaded at this time.

Does the malwarebytes work on Linux??

Thanks

Oh sorry, I missed that, It's been a long week :)

No Malwarebyes won't work on Linux and there is no need to run it anyway.

HI,

I can also see the Horizontal black lines in text while scrolling in Firefox only some times see attached screen-shot. I'm using firefox on ubuntu 12.04

Is it something related font rendering or display issue..?

Start Firefox in Safe Mode to check if one of the extensions (Firefox/Tools > Add-ons > Extensions) or if hardware acceleration is causing the problem (switch to the DEFAULT theme: Firefox/Tools > Add-ons > Appearance).

• Do not click the Reset button on the Safe mode start window or otherwise make changes.

• https://support.mozilla.org/kb/Safe+Mode

Try to disable hardware acceleration in Firefox.

• Edit > Preferences > Advanced > General > Browsing: "Use hardware acceleration when available"

• https://support.mozilla.org/kb/Troubleshooting+extensions+and+themes

The above solutions are not working. Fix these bugs in firefox please. No issues with chrome