See this article -> Firefox hangs or is not responding - How to fix

Check and tell if its working.

It's not just Firefox that hangs -- it's the WHOLE SYSTEM. As in no cursor movement, no CPU usage, it just comes to a dead stop and nothing will "fix" this except a hard reboot. I tried creating a new profile, as suggested on one of the forum responses -- and the MINUTE I opened Firefox on the new profile, the computer instantly locked up completely and had to be hard-rebooted once again. Right now I'm running in safe mode with Networking -- I'm going to see how long I can function in this mode, and if it works to solve the issue. I'm hoping that this will work, so that I can then translate from running in safe mode to find out what - other than Firefox - might be causing an issue. Although the problem didn't exist until I upgraded to v12, and I have literally uninstalled and reinstalled (or completely removed) everything that has been updated or changed since that day (hence the Adobe re-installs, etc.). I even made an attempt prior to the new-account creation, to screen-shot my Windows Task Manager window to show what programs were running, but when I opened my graphics program to crop down the image, the system locked up. I have (literally) rebooted my computer four times in the last hour... needless to say, I'm more than a little frustrated!

Does your system till hangs-up even if you uninstall Firefox ??

I haven't tried uninstalling it completely and then running for any extended period. Earlier today, I uninstalled it completely, then reinstalled it from scratch, updated all the plug-ins, etc. I *did* manage to keep it running this time long enough to find out what was running while I was in safe mode versus "normal" mode with Windows... now comes the process of elimination to find out what's different that's causing the issue. When I first re-installed Firefox, I had a number of crash/lockup-free hours, but since then have been having constant issues. I share this computer with my son, and he runs via Internet Explorer, while I use Firefox, saving us from having two sets of bookmarks, having to log out on things such as e-mail and Facebook, etc. The only thing that he runs that I don't is Steam -- which hasn't caused an issue prior to now.

• Try Starting Firefox in -> Diagnose Firefox issues using Troubleshoot Mode to check if your add-ons/extensions are causing the problems.
• Also see this article -> Troubleshoot extensions, themes and hardware acceleration issues to solve common Firefox problems

Check and tell if its working.

Ok - uninstalled Firefox completely, then ran a thorough virus scan. Did find a corrupted file... from a program that's been here for months and hasn't been used in a LONG time. *shrug* Just downloaded and re-installed Firefox, and I had done the first step on the recommended extensions & themes page, but not removed the theme. I just disabled that -- we'll start there and see if that works. *crosses fingers*

Since you mentioned that you are scanning your system from possible threats, see the following too.

-> Is my Firefox problem a result of MALWARE ??

• Popups Not Blocked - http://kb.mozillazine.org/Popups_not_blocked

-> Do a MALWARE check with these Malware Scanning programs. 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. Also, Close All other Applications (softwares) before Starting to Run Scans.

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

Your Malware undetectable by most anti-malware programs (maybe because randomly named) may still be present and has other hidden symptoms, see this -> http://en.wikipedia.org/wiki/Backdoor_%28computing%29

• IF this Malware is a Rookit, try this free Kapersky's tool:
• Anti-Rootkit Utility - TDSSKiller -> http://support.kaspersky.com/faq/?qid=208283363

• nods* I've scanned it with Spybot, C-Cleaner, and Avast! anti-virus. I ran all three while Firefox was uninstalled, and (with the mentioned exception) found no issues. I am, however, uploading the screen captures (hopefully!) of the safe-mode Task Manager versus the normal-mode Task Manager windows. I have disabled nearly everything on the normal-mode Task Manager at this time (to match the safe mode version) and am going to try, via process of elimination today, to determine which one of the normal-mode items is the culprit, assuming that the problem doesn't reappear. If you see anything in the "normal mode" Task manager that rings a bell as a probable issue, let me know. Fresh eyes might see something I'm missing.

• Update*

I ran the anti-rootkit scanner from Kaspersky as suggested -- nothing found. When I eliminated everything running to match the safe-mode Task Manager, I had no issues (and still had my anti-virus program available, which I don't in safe mode). I closed out Firefox, no problems... until my son opened Internet Explorer. The minute he did so, the computer locked up again and had to be hard rebooted. *sigh* I'm going to give it a few more hours, but the next freeze/lockup is going to send me to another browser, as much as I dislike leaving Firefox. I'm not willing to destroy my hard drive over a browser error.

Create a New Profile as a test to check if your current profile is causing the problems.

• Basic Troubleshooting - Make a New Profile
• Now start Firefox using this newly created profile.

IF that New Profile works then you can recover your History, Bookmarks and Passwords from the Old Profile.

• Recover important data from an old profile

Check and tell if its working.

Well, to be honest... after a few days of considering doing this, and continuing to see the same problems even with nothing extraneous running, I made the decision to move to another browser. A few releases back, I had to go in and modify the code to keep the plug-in container from locking up my system due to overuse of memory. While that was mildly irritating, this constant freeze-up issue was the proverbial straw that broke the camel's back. When I have to start modifying the base code on a program just to make it functional, as the end user, that tells me that the designers are more concerned with doing the more-and-bigger instead of fixing the issues. Thank you for all the help - it was very much appreciated.  :)

Are you 100% SURE that it is Firefox that locks your system up? Have you installed any other programs recently?

Also, check your memory in Task Manager to see if you have enough memory to run the applications you have.

I'm absolutely certain that it's Firefox. I uninstalled Firefox and everything that had been installed or even updated from the time I upgraded to version 12, and the lock-ups continued. I ran Spybot, C-Cleaner, my anti-virus, both with Firefox installed and uninstalled. While FF was uninstalled, I had no issues whatsoever with the lockups, but as soon as I reinstalled it, the problem returned. I tried shutting down everything that was running in the background except the Windows necessities and my anti-virus, with no luck. As of a few hours ago, I uninstalled Firefox for the final time and installed Google Chrome. I've been jumping pages, running app games, and a number of other tasks that seemed to be triggers for the lock-up without issue, and all background programs are still running. I hated to move from Firefox, but it's simply more trouble than it's worth.

I think before move to another browser you must re-thing mha007 replies above to see what happen in safe mode, and to enable one-by-one your plug-ins to see if the problem is there. Also (as mha007 suggest) to make a new profile and check it there, is an excellent option.But your choice is yours.

thank you

ideato, I've done everything suggested with the exception of creating a new profile. As I mentioned, it seems that having to practically re-write the code for the browser in order to be able to use it -- a step that might not work and cause even more frustration -- is more than I'm willing to do. I've been trying to keep my patience with Firefox since the issues with the plug-in container memory, but after more than a week of being in the middle of something only to have to stop, hard re-boot my computer, and start again... it's just too much irritation. I've even gone to the lengths of shutting down everything running in the background while Firefox was in use -- including the sound controls, video card drivers, my screensaver, you name it -- and none of it helped. Just the fact that I can run Google Chrome and still have my sound working, be able to access more than one website at a time, trust that I can open my word processing program and work without losing pages of writing... all without wondering constantly when the computer is suddenly going to lock up... is a relief. I don't know why v12 and my computer didn't get along, and may never know. But I appreciate everyone trying to find a solution that worked. Unfortunately, none of them helped my issue, but I hope that others who are having the same problems are able to use the suggestions to "cure" whatever is ailing v12 on their system.

Perform the suggestions mentioned in the following articles:

• Troubleshooting Plugins
• http://kb.mozillazine.org/Issues_related_to_plugins

Check and tell if its working.

I've done that, as well. I disabled ALL of my plug-ins, restarted, and still had the same issue. I then uninstalled and reinstalled both Java and Adobe (the main ones that are used) to no avail. I removed everything incompatible with v12, and was still locking up as often as two to three times an HOUR by the time I finally uninstalled it last night. Since doing so, I've not had any lock-ups or issues of any sort with the system.

As you mentioned in your previous reply "I've done everything suggested with the exception of creating a new profile."

This is the last shot i can call. Your Firefox Profile might have got corrupted. Perform the suggestions mentioned below:

1) Restart your Windows in Safe Mode as described in the following article:

• http://windows.microsoft.com/en-us/windows-vista/start-your-computer-in-safe-mode

2) Uninstall Firefox as described in this article -> Uninstall Firefox from your computer

• Restart your system

3) Download latest Firefox version from one of the following links using some other Web Browser:

• http://www.mozilla.org/en-US/firefox/update/
• http://www.mozilla.com/en-US/firefox/new/
• http://www.mozilla.com/en-US/firefox/fx/
• http://www.mozilla.com/en-US/firefox/all.html

4) Install Firefox 12 as described in this article -> How to install Firefox on Windows

• DON'T START FIREFOX YET

5) Create a New Profile as described in this article -> Basic Troubleshooting - Make a New Profile

• Now start Firefox using this newly created profile.

Check and tell if its working.

6) IF that New Profile works then you can recover your History, Bookmarks, Passwords,etc. from the Old Profile, as described in this article -> Recover important data from an old profile

Which security software (firewall, anti-virus) do you have?

If your computer locks then that is usually caused by a system service or one of the drivers that aren't compatible, so make sure that all software is updated to the latest versions.

The anti-virus program that I'm using is Avast! Home edition. I also have Spybot that's run on a weekly basis and C-Cleaner, as well. All of those are up to date and have never caused an issue before now. As for creating a new profile - as I said, it feels like I have to go in and re-write the code for the browser. I did it once when the plug-in container was using too much memory, but to have to do it a second time... without a guarantee that it will fix the issue... is just too much. My computer time is relaxation time - and having to re-write code, not to mention constantly being on guard that I'm not doing anything I might lose if the system decides to lock, is NOT relaxing. I was able to import all of my data and bookmarks to Chrome, and will probably stick with it, because since I uninstalled Firefox for the final time, I've not had a single issue.