Check that the computers firewall lets Firefox access the web. Next, run two or more of the mal-ware checking programs (below). Finally, after you have done all that, go to Mozilla.org and download the full installer.

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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
• 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.

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

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

Thanks for the reply. I opened the Windows Firewall window and saw the following message: "Windows Firewall is not using the recommended settings to protect your computer." I then clicked the "Use Recommended Settings" button, but received the following error: "Windows Firewall can't change some of your settings. Error 0x80070424." I figured I may as well scan my computer with the list of malware programs you suggested and some infected files were found and removed. However the ESET program found some trojans, along with some other files, but it only removed the non-trojan files. I then uninstalled FF and reinstalled it using the link you provided, but unfortunately, after restarting my computer, I was greeted with the same browser freeze. Any ideas?

How many of the mal-scanners did you use? If you think there is still a problem, use another scanner also. Different scanners work in different ways, so always use several programs. After the next scan, try to post the results here. Good luck.

After a reset, Firefox works normally until you exit out and try to restart it again? And then the problem occurs immediately, and doesn't require that you shut down and restart Windows?

@FredMcD: I tried all of the ones you listed, including the Microsoft Security Essentials, with which I performed a full scan, but it froze on me. I'll see if I can try that one again with some success. I tried the ESET again last night, fortunately (or unfortunately) it found no threats.

@jscher2000: When I first start up the computer I have the freezing issue with FF. Once I reset it, it's fine, even when I close the browser window and open FF again. It's only when I restart the computer that the problem occurs, which is once at the start of the day.

Hi Lefky, if you have the patience for an experiment, could you try this? The idea is to save a copy of your Firefox settings folder so that you can compare the pre-shutdown folder contents with the post-startup folder contents.

To do the comparison, I suggest a program like Winmerge: http://winmerge.org/

Before shutting down Firefox for the day, open your currently active Firefox settings folder (your profile folder) using:

Help > Troubleshooting Information > (in the first table) "Show Folder" button

Leave this folder open, then switch back to Firefox and Exit

Pause 10 seconds while Firefox finishes its cleanup, then in the address bar above the file list, click Profiles. There you should see your active profile folder, although you might also see others.

Right-click > Copy your profile folder and paste it somewhere far away, like your Documents or Downloads folder, or an external drive.

You might want to copy the paths of the two folders and paste them into a Notepad or Word document for future pasting, as that will speed the process of running the folder comparison.

After restarting Windows,* you can use Winmerge to compare the contents of the two folders to see what might be changing when Windows starts up.

Anything interesting happening?

* Before starting Firefox

I attempted the above steps, but wasn't sure what you meant by two folders. I followed the steps up to where I clicked the "Show Folder" button, closed Firefox, then clicked on "Profiles" and copied the active folder to my documents. So, I have that one, but didn't know where the second folder came from.

Hi Lefky, the second folder would be the profile folder after you restart Windows and the problem reappears. So actually, it's the same folder before shutdown and after restart.

Sorry for the delayed response. I think the problem may be Flash related. Several days ago I reset Firefox, as I have been doing for a while now, but I didn't install the Flash player right away. The next couple of days Firefox was functioning fine, and I still hadn't installed Flash. Just last night, however, I installed Flash again and today I experienced the same freezing issue. I want to have Flash installed for videos, etc., but don't want to reset FF the following day every time. Any way of correcting this?

Crashes or other problems with certain multimedia content in Firefox (such as Youtube videos and Flash animations or games) can often be resolved by performing the steps 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

On Windows Vista and above, you can disable Flash protected mode by following the instructions on these pages:

• http://forums.adobe.com/thread/1018071#TemporaryWorkaround
• http://kb.mozillazine.org/Flash#Disabling_Protected_Mode_in_Flash_11.3

(See this Adobe blog post for technical details about Flash protected mode.)

Please tell us if this helped!