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

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

Many site issues can be caused by corrupt cookies or cache.

• Clear the Cache

How to clear the Firefox cache {web link}

and

• Remove Cookies

This will log you out of all sites you're logged in to. Press the <Alt> or <F10> key to bring up the tool bar. Followed by;

Windows; Tools > Options Linux; Edit > Preferences Mac; application name > Preferences

Then Privacy. Under History, select Firefox will Use Custom Settings. There is a button on the right side called Show Cookies.

If there is still a problem, Start Firefox in Safe Mode {web link} While you are in safe mode; Press the <Alt> or <F10> key to bring up the tool bar. Followed by;

Windows; Tools > Options Linux; Edit > Preferences Mac; application name > Preferences

Then Advanced > General. Look for and turn off Use Hardware Acceleration.

Poke around safe web sites and see if there is still a problem. Then restart.

I followed theses instructions, I turned off acceleration hardware and default to firefox home page. while in safe mode I notice when home page come up I had a full page no black and gray. I then restarted and then the home page come up with black/gray lower page. I also don't save history and etc, I did clear this? Any more suggestions please. Thank you

Also When I go to internet explorer I don't have this problem.

I did this as suggested. I removed acceleration hardware check mark and used fire fox home page as default. When I did this in safe mode I noticed i had a full page with no black or gray at the bottom. It was perfect. After I restarted then the home page came up with black and gray. So I still have the same problem. Please help again. Thank you.

Also when I go to internet explorer, then I don't have this problem.

Could you try updating your extensions and disabling any that aren't essential? You can do that on the Add-ons page. Either:

• Ctrl+Shift+a
• "3-bar" menu button (or Tools menu) > Add-ons

In the left column, click Extensions.

To update, look for the "gear" button above the list > Check for Updates

Then review your list for anything you don't plan on using for the next 24 hours and try disabling it.

Any improvement?

I tried this, and restarted and no improvement. Thanks

What extensions are still enabled? You can pull a list from the following page (3 different ways you can get there):

• "3-bar" menu button > "?" button > Troubleshooting Information
• Help menu > Troubleshooting Information
• type or paste about:support in the address bar and press Enter

In the upper left corner is a button labeled "Copy text to clipboard" that you can use to grab all the info on the page. Then paste into a reply. You can delete the part that starts from "Important Modified Prefernces" down to the end if the forums says there is too much input.

Media Player Plus 0.94.61 Muvic 1.1 The are the only extensions enabled

Hmm, do you recall installing those? Could you try disabling both of them and see whether that helps?

No I don't recall installing them. I have disabled and restarted my computer. No change??

I went into safe mode and the lower half of screen is the same blank. I have done a system restore to an earlier date several times and each time I do this I get a full screen and no problems. But when I close out and start my computer a Mozilla screen comes up loading something and then I have the same problem again. I go to internet explorer and don't have the problem??

Two other thoughts:

"Ask to Activate" Plugins

Firefox 30 switched the less common plugins from "Always Activate" to "Ask to Activate" so that sites need to ask your permission to run them. Some plugins that interact with the user interface are glitchy in this mode.

To test whether that is the issue, try switching each of your less common plugins to one of the other options:

• Always Activate - all sites can use the plugin without specific permission
• Never Activate - no sites can use the plugin (unless you give them permission through the Permissions page of the Page Info dialog while viewing the site)

To make this change open the Add-ons page using either:

• Ctrl+Shift+a
• "3-bar" menu button (or Tools menu) > Add-ons

In the left column, click Plugins. Look for the ones set to "Ask to Activate" and change those to "Never Activate" as a test.

Create a new window (Ctrl+n or Ctrl+Shift+p) to test. Any difference?

Damaged Program Files

The basic Firefox UI is built from a file in the Firefox program folder. You don't need to uninstall to replace the program folder, you can use this procedure:

(1) If needed, download a fresh installer for Firefox 30 from https://www.mozilla.org/firefox/all/ to a convenient location. (Scroll down to your preferred language.)

(2) Exit out of Firefox.

(3) Rename the folder

C:\Program Files\Mozilla Firefox

to

C:\Program Files\OldFirefox

(4) Run the installer you downloaded in #1. It should automatically connect to your existing settings.

Does the lower part of the tab work normally?

Note: Some plugins may exist only in that OldFirefox folder. If something essential is missing, look in these folders:

• C:\Program Files\OldFirefox\Plugins
• C:\Program Files\OldFirefox\browser\plugins

Do a clean reinstall and delete the Firefox program before (re)installing a fresh copy of the current Firefox release.

• Download the full Firefox installer and save the file to the desktop
  http://www.mozilla.org/en-US/firefox/all.html

If possible uninstall your current Firefox version to cleanup the Windows registry and settings in security software.

• Do NOT remove "personal data" when you uninstall your current Firefox version, because this will remove all profile folders and you lose personal data like bookmarks and passwords including data in profiles created by other Firefox versions.

Remove the Firefox program before installing that newly downloaded copy of the Firefox installer.

• (32 bit Windows) "C:\Program Files\Mozilla Firefox\"
• (64 bit Windows) "C:\Program Files (x86)\Mozilla Firefox\"

• It is important to delete the Firefox program to remove all the files and make sure that there are no problems with files that were leftover after uninstalling.
• http://kb.mozillazine.org/Uninstalling_Firefox

Your bookmarks and other personal data are stored in the Firefox profile folder and won't be affected by an uninstall and (re)install, but make sure that "remove personal data" is NOT selected when you uninstall Firefox.

If you keep having problems then also create a new profile.

• http://kb.mozillazine.org/Profile_folder_-_Firefox
• http://kb.mozillazine.org/Profile_backup

• http://kb.mozillazine.org/Standard_diagnostic_-_Firefox#Clean_reinstall

I followed your instructions deleted , and reinstalled. I had done this once before. no change, I didn't change profile. I am not clear on understanding this? Is this a must? If so can you share with me the details? Thank you

Does anyone have any ideas on what I can do to get my screen back to normal?

Here's a more specific recipe:

Create a new Firefox profile

A new profile will have your system-installed plugins (e.g., Flash) and extensions (e.g., security suite toolbars), but no themes, other extensions, or other customizations. It also should have completely fresh settings databases and a fresh cache folder.

Exit Firefox and start up in the Profile Manager using Start > search box (or Run):

firefox.exe -P

Don't delete any profiles here!

Any time you want to switch profiles, exit Firefox and return to this dialog.

Click the Create Profile button and name it something like TEST. Skip the option to change the folder location and save your new profile. Then start Firefox in the TEST profile you created.

Any difference?

When returning to the Profile Manager, you might be tempted to use the Delete Profile button on TEST. But... it's a bit too easy to accidentally delete your "real" profile, so I recommend resisting the temptation. If you do want to clean up later, I suggest making a backup of all your profiles first in case something were to go wrong.

Do you use Trend Micro antivirus software or toolbar? If you do so, please try to update your Trend Micro software or disable Trend Micro add-ons in Firefox.

Thank you very much. I had a 2012 Trend Micro downloaded and disabled. So once I deleted and connected with Trend Micro. The Problem black/gray screen on the lower half of my screen went away. So thank you so much and thank all of you that took the time to try to help me.