upgrade the firefox version and check it . goto help->about firefox and upgrade it.

Same problem and have the latest Firefox, v. 20.0. Mac OS 10.6.8 - Don not care to upgrade the OS yet but its the same problem. Locks up so bad I have to force a shutdown. Mouse still moves but nothing is accessable nor get the force quit option to come up.

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
• TDSSKiller - AntiRootkit Utility

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

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

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

I am on a Mac so windows malware aint it. Its an issue with the Flash plugin in some way. If I leave it disabled, it does not lock me up and yes, it is the current release.

I am making do by leaving the flash plugin disabled till I really really need to use it. That works ok unless I forget to turn it off after I am done, or sometimes it will lock me out trying to get done what i needed to do regardless, but I can go days without the issue and it only does it when flash is enabled. Perhaps my support questions should be directed at Adobe about this issue.

Recent crashes of certain multimedia contents (this includes Youtube videos, certain flash games and other applications) in conjunction with Firefox are most probably caused by a recent Flash 11.3 update and/or a malfunctioning Real Player browser plugin.

In order to remedy the problem, please perform the steps mentioned in these Knowledge Base articles:

Flash Plugin - Keep it up to date and troubleshoot problems

Adobe Flash plugin has crashed - Prevent it from happening again

Flash 11.3 doesn't load video in Firefox

Other, more technical information about these issues can be found under these Links:

http://forums.adobe.com/thread/1018071?tstart=0

http://blogs.adobe.com/asset/2012/06/inside-flash-player-protected-mode-for-firefox.html

Please tell us if this helped! Please check if all your plugins are up-to-date. To do this, go to the Mozilla Plugin Check site.

Once you're there, the site will check if all your plugins have the latest versions. If you see plugins in the list that have a yellow Update button or a red Update now button, please update these immediately.

To do so, please click each red or yellow button. Then you should see a site that allows you to download the latest version. Double-click the downloaded file to start the installation and follow the steps mentioned in the installation procedure.