Sometimes a problem with Firefox may be a result of malware installed on your computer, that you may not be aware of.

You can try these free programs to scan for malware, which work with your existing antivirus software:

• Microsoft Safety Scanner
• MalwareBytes' Anti-Malware
• Anti-Rootkit Utility - TDSSKiller
• AdwCleaner (for more info, see this alternate AdwCleaner download page)
• Hitman Pro
• ESET Online Scanner

Microsoft Security Essentials is a good permanent antivirus for Windows 7/Vista/XP if you don't already have one. Windows 8 has antivirus built-in already.

Further information can be found in the Troubleshoot Firefox issues caused by malware article.

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I tried all those with mine...nothing...and no way to screenshot...the only solution was completely ridding my computer of Mozilla Firefox. I even had the Tech at aol personally run a scan on my computer, it had no viruses.

In another thread you wrote:

pc keeper and media player 12.2 are blanketting my screen. theses are ONLY with firefox and they are overwellming.

Usually this kind of problem is caused by an add-on. Here's my suggested procedure for tracking down and cleaning up bad add-ons and other ad injectors. I know it seems long, but it's not that bad.

(1) Open the Windows Control Panel, Uninstall a Program. After the list loads, click the "Installed on" column heading to group the infections, I mean, additions, by date. This can help in smoking out undisclosed bundle items that snuck in with some software you agreed to install. Take out as much trash as possible here.

(2) Open Firefox's Add-ons page using either:

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

In the left column, click Plugins. Set nonessential and unrecognized plugins to "Never Activate".

In the left column, click Extensions. Then, if in doubt, disable (or Remove, if possible) unrecognized and unwanted extensions.

Often a link will appear above at least one disabled extension to restart Firefox. You can complete your work on the tab and click one of the links as the last step.

Any improvement?

If Firefox is so messed up that you cannot get to the Add-ons page, try starting Firefox in its Safe Mode where extensions are disabled.

If Firefox is not running: Hold down the Shift key when starting Firefox.

If Firefox is running: You can restart Firefox in Safe Mode using either:

• "3-bar" menu button > "?" button > Restart with Add-ons Disabled
• Help menu > Restart with Add-ons Disabled

and OK the restart.

Both scenarios: A small dialog should appear. Click "Start in Safe Mode" (not Refresh).

(3) You can search for remaining issues with the scanning/cleaning tools listed in our support article: Troubleshoot Firefox issues caused by malware. These on-demand scanners are free and take considerable time to run. If they finish quickly and especially if they require payment, you may have a serious infection. I suggest the specialized forums listed in the article in that case.

Success?

Recently, several users have posted about malware that appears to insert two configuration files into the Firefox program folder. Uninstalling the malware, not surprisingly, doesn't clear out those files. In case you have something similar, I suggest:

Clean Reinstall

We use this name, but it's not about removing your settings, it's about making sure the program files are clean -- and do not contain alien code files. As described below, this process does not disturb your existing settings. Do NOT uninstall Firefox, that's not needed.

(1) Download a fresh installer for Firefox 37.0.1 from https://www.mozilla.org/firefox/all/ to a convenient location. (Scroll down to your preferred language.)

(2) Exit out of Firefox (if applicable).

(3) Rename the program folder

(64-bit Windows folder names)

C:\Program Files (x86)\Mozilla Firefox

to

C:\Program Files (x86)\OldFirefox

(32-bit Windows folder names)

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.

Any difference?

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

• \OldFirefox\Plugins
• \OldFirefox\browser\plugins

Hi AzizalSaqr, did you still have the problem with the blank white box with the gray bar and checkbox? That is caused by AOL's extension. In order to remove the extension, you need to start Firefox in its Safe Mode so that the extension doesn't start up. Or I suppose there's probably a way to track it down and physically remove it from disk.

I've had all evidence of Firefox professionally removed from my computer, I will not be installing it again.

Only this problem you encountered was Not due to any version of Firefox from www.mozilla.org

Firefox from mozilla.org is sadly becoming one of the fewer softwares that does not come bundled with anything questionable in any form.

There are things out there that may not be easy to find depending on what you scan with and may only target the default browser or say Firefox specifically.

Also if you installed extensions, especially ones from outside of the addons.mozilla.org host (a.m.o tries to host only good ones) you can potentially encounter issues like you had when trying to use Firefox.