Try these out and let us know how you are doing.

Type about:preferences#advanced<Enter> in the address bar.

Under Advanced, Select Network. Look for Configure How Firefox Connects and press the Settings button. Check the settings.

Some problems occurs when your Internet security program was set to trust the previous version of Firefox, but no longer recognizes your updated version as trusted. Now how to fix the problem: To allow Firefox to connect to the Internet again;

• Make sure your Internet security software is up-to-date (i.e. you are running the latest version).
• Remove Firefox from your program's list of trusted or recognized programs. For detailed instructions, see

Configure firewalls so that Firefox can access the Internet. {web link}

Start Firefox in Safe Mode {web Link} by holding down the <Shift>
(Mac Options) key, and then starting Firefox. Is the problem still there?

I checked my network settings and mine is set to use system proxy settings. If I change it, click ok and check but it just goes back to use system proxy settings. not sure if that is an issue.

I use windows firewall in win 7 and I deleted the firefox entry and added it again but made no difference. Still hangs forever.

I tried safe mode and still it hangs. Also won't shutdown in safe mode either. I have to restart.

kewltalon said

If I change it, click ok and check but it just goes back to use system proxy

https://support.mozilla.org/en-US/kb/how-to-fix-preferences-wont-save

windows firewall I deleted the firefox entry and added it again

Don't add it yourself, let the system do it.

Also won't shutdown in safe mode either. I have to restart.

This is not a cure but will make it easier if Firefox locks up in Windows. https://support.mozilla.org/questions/997866 {web link}

OK, I tried changing settings using the link provided but none of that worked. Everything reset to default.

I deleted the entry and let windows build the entry for me. No luck. Still grey spinning circle indefinitely.

I tried the taskkill of firefox but that wouldn't kill firefox from task manager. I am really stumped. Chrome and IE work flawless, as flawless as IE can. LOL

I should note I am getting errors in event viewer for Firefox too.

Do a malware check with several malware scanning programs on the Windows computer. Please scan with all programs because each program detects different malware. All these programs have free versions.

Make sure that you update each program to get the latest version of their databases before doing a scan.

• Malwarebytes' Anti-Malware:
  http://www.malwarebytes.org/mbam.php
• AdwCleaner:
  http://www.bleepingcomputer.com/download/adwcleaner/
  http://www.softpedia.com/get/Antivirus/Removal-Tools/AdwCleaner.shtml
• SuperAntispyware:
  http://www.superantispyware.com/
• Microsoft Safety Scanner:
  http://www.microsoft.com/security/scanner/en-us/default.aspx
• Windows Defender:
  http://windows.microsoft.com/en-us/windows/using-defender
• Spybot Search & Destroy:
  http://www.safer-networking.org/en/index.html
• Kasperky Free Security Scan:
  http://www.kaspersky.com/security-scan

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

• Anti-rootkit utility TDSSKiller:
  http://support.kaspersky.com/5350?el=88446

See also:

• "Spyware on Windows": http://kb.mozillazine.org/Popups_not_blocked
• https://support.mozilla.org/kb/troubleshoot-firefox-issues-caused-malware

kewltalon said

I tried the taskkill of firefox but that wouldn't kill firefox from task manager.

This is not a cure but will make it easier if Firefox locks up in Windows. https://support.mozilla.org/questions/997866 {web link}

I should note I am getting errors in event viewer for Firefox too.

Can you try to take a snapshot to show them ti us?

Ok I was able to solve it. Not in the direction I thought.

Cor-el I did do several scans using almost every one of the programs that you suggested. And after everything kept coming up clean I decided to look at what else I was using.

I uninstalled Lastpass password manager and firefox and reinstalled both after a clean reboot. And everything seems to be working so far. I have slowly copied over my saved settings from my old profile and again so far so good. I have even been able to adjust settings and save them.

It appears the update to firefox was not compatible with Lastpass or there was some corruption that affected firefox. Somehow lastpass locked firefox from connecting to the internet and shutting down correctly even after a clean install and safe mode. Hopefully this has solved the issue.

Thanks to Fred and cor-el for all the trouble shooting advice.

That was very good work. Well Done. Please flag your last post as Solved Problem so other will know.

LastPass has caused users issues in the past. Please contact their support page.

Unfortunately the bug came back. I still can't use firefox. Going to revert to 35. Even uninstalling lastpass helps but only for a few hours then right back to locked up.

A post was flagged as Solved Problem. Please remove that flag. If you don’t, others that can help may not read this post.

Did you get any crash reports? Have you tried Safe Mode?

Describe what is now happening. Please give some details.

Hi Fred

Reinstalling Lastpass and Firefox yesterday worked yesterday. Today, Firefox locked up and wouldn't load any web pages. It also wouldn't quit, the browser window closes but the firefox.exe process runs in the background preventing it from restarting. I have to reboot to clear the process.

Safe mode is the same. There was no change. I tried a new profile again today and no luck. Loads once then locks or freezes. Reboot fixes temporarily.

I have uninstalled Firefox 36, left Lastpass and installed Firefox 35.0.1 and so far it is working. FF36 seems totally uncompatible with my PC. And I need it for my business hence reverting to get it up and running.

I have found some info on FF36 and this is exactly the issues I face. I dont have time to try them yet.

http://forums.mozillazine.org/viewtopic.php?f=23&t=2882597&start=15

http://forums.mozillazine.org/viewtopic.php?f=38&t=2474849

A couple suggestions in these threads I will try. tracking protection and tab preload.

As for crash reports, yes everytime I tried to close firefox the first time after a reboot, it sent a crash report to Mozilla.

Some of your crash reports weren’t sent to the Mozilla Servers.

In the address bar, type about:crashes<enter>. Note: If any reports do not have BP in front of the numbers, click it and select Submit.

Using your mouse, mark the most resent 7 - 10 crash reports, and copy them. Now go to the reply box below and paste them in.

Unfortunately, I completely wiped the history out before I re-installed firefox 35. Unless there is a different area these crash reports may be stored. I search the app data area and see.

The reasons why they were hanging in 2010 and 2004 are too old to apply to this.

However since it is freezing and there are no crash reports and it sounds like the root cause was Last Pass this might be a nice starting point.

Currently a crash hang report is created once the application force quits, but it does not sound like this is happening.

Reboot works, and a new profile does not, and uninstalling last pass Firefox eventually locks up, freezes (this is contradicting Last Pass being the root here)

If we can narrow down the exact steps that lock up Firefox we can try to get more than one person to reproduce this and confirm.

I tried to reproduce this and it downloaded an older version of last pass version 3.1.1 instead of 3.1.92 which version is locking up? (originally yours listed 2.5.5.0)

It is not freezing after a few hours, and I am beginning to think it might be something else. Is there a particular site this happens on constantly?

I am almost positive it is last pass that is causing it to hang indefinitely. It makes no difference what site i am using, firefox becomes completely unresponsive and then cannot be shutdown without a reboot.

The issue seems to have something to do with the way lastpass connects to the internet. I am using firefox 35 and it works but if I lose internet connection it reproduces the hang. Once internet connection is re-established firefox responds and I can shut it down or continue using it. I am going to update firefox and try again. Also I have a support ticket open with lastpass and they directed me to a different version of lastpass to download and try.

Will report back with results.

I allowed firefox to update and the problem persists. Totally unresponsive after about 1 to 2 minutes. Cannot shut down have to reboot.

Will try the alternative lastpass download from their support.

Ok, uninstalled lastpass and reinstalled using the lastpass download they suggested and no luck. Works for about a minute and then hangs. I am getting crash reports to when I try to shutdown. Hopefully this will help you track this.

If I roll back to firefox 35 and use everything runs normally. Firefox 36 does not run at all for me. It just hangs after a few clicks of the mouse. I am at a loss to explain.

Firefox 36 will work only if I leave it without any addons. But I need my passwords and such so that won't help.

Start Firefox in Safe Mode {web Link} by holding down the <Shift>
(Mac Options) key, and then starting Firefox. Is the problem still there?

Disable LastPass. Is the problem still there?

Safe mode the problem still exists. No change works for about one minute then everything just hangs and won't kill process in background.

I disabled lastpass and the issue is still there.