try Refresh Firefox - reset add-ons and settings

Let me know if it works.

Try to disable hardware acceleration in Firefox.

• Tools > Options > Advanced > General > Browsing: "Use hardware acceleration when available"
• https://hacks.mozilla.org/2010/09/hardware-acceleration/

• https://support.mozilla.org/kb/how-do-i-upgrade-my-graphics-drivers

Do a malware check with some malware scanning programs on the Windows computer.
You need to scan with all programs because each program detects different malware.
Make sure that you update each program to get the latest version of their databases before doing a scan.

• http://www.malwarebytes.org/mbam.php - Malwarebytes' Anti-Malware
• http://www.superantispyware.com/ - SuperAntispyware
• http://www.microsoft.com/security/scanner/en-us/default.aspx - Microsoft Safety Scanner
• http://www.microsoft.com/windows/products/winfamily/defender/default.mspx - Windows Defender: Home Page
• http://www.safer-networking.org/en/index.html - Spybot Search & Destroy

You can also do a check for a rootkit infection with TDSSKiller.

• http://support.kaspersky.com/viruses/solutions?qid=208280684

See also:

• "Spyware on Windows": http://kb.mozillazine.org/Popups_not_blocked

I've been having most of the problems with Flash and Shockwave panels when browsing the Internet. Numerous Flash Player crashes.

Also, I am running Microsoft Security Essentials and keep it up to date. I run Malwarebytes Antimalware weekly. I keep my registry clean with Registry Mechanic daily and CCleaner weekly.

You can check for problems caused by a recent Flash 11.3 update and possibly try these:

• downgrade to Flash 11.2 or 10.3
• disable protected mode in Flash 11.3 and later
• disable hardware acceleration in the Flash plugin
• http://kb.mozillazine.org/Flash#Flash_Player_11.3_Protected_Mode_-_Windows

• https://support.mozilla.org/kb/flash-113-doesnt-load-video-firefox
• https://support.mozilla.org/kb/flash-113-crashes

I've disabled hardware acceleration and it appears to be more stable. I will report back if the problem is solved.