Unfortunately, many user have similar problems. I spoke to a tech at Microsoft Support. One suggestion was to run a registry cleaner / repair.

Many users have reported problems with Firefox refusing to close Even when using the Task Manager or the TaskKill program. I had a chat with a Microsoft tech on this issue; https://pastebin.mozilla.org/8826478

No joy with that - tried to close it with both of the programs suggested and still get an 'Access Denied' message, even when running as an Administrator?

'Error Terminating Process: Access Denied'

Firefox takes some time to shut down, clean up files, etc., so please allow a minute before starting it up again.

A couple of other users have reported that starting in Firefox 36, they will suddenly not be able to load any sites, and the only workaround so far is what you're doing. There may be some common variable here that isn't obvious yet.

• Server not found in Firefox 36
• All sites stop loading after Firefox is open for a period of time

Could you check on whether Firefox has gathered any data on its inability to shut down properly? If so, it would appear on the about:crashes page described in the last section of this article: Troubleshoot Firefox crashes (closing or quitting unexpectedly).

You can submit that crash data to Mozilla using the links on the about:crashes page, and share it with forum volunteers by posting the crash report IDs or full URLs to the reports on the crash-stats server. Hopefully this will surface the cause of that problem.

Unfortunately, even after waiting an hour to let it settle down and sort itself out, I've never had a crash report - it just hangs in the background processes of my Task Manager. I've just tried using Malwarebytes, AVG, Superantispyware, Windows Defender and a few others, just to make sure, although as far as I can see it's still happening. There doesn't appear to be any particular physical thing that sets it off - I could have left the computer for a while to find nothing has happened for it to hang and give me 'connecting' out of nowhere. I could have spent anywhere from 30 seconds to two hours using it. I had to restart my computer to post this, only for it to stall again, for me to give up and resort to IE.

When you installed Firefox 36, did Windows Firewall ask to to approve new access rules? If so, let's try deleting those in case some kind of network activity is hanging. I would close Firefox when doing this, assuming you can.

I'm not quite sure where that is in Windows 8, but on Windows 7:

Control Panel > System and Security > Windows Firewall > Advanced Settings

In the left column, click Inbound Rules and remove all rules for Firefox.

It did ask to approve something, yes. Changed the settings as you suggested in Windiws Firewall. Worked okay for about two minutes but it's gone again, sorry! Good try though, hadn't heard that one before!

I was having this same exact problem for the last week. It started happening after Firefox updated. I tried a few different things that didn't help. I tried uninstalling and reinstalling which didn't help either. I finally fixed the problem tonight.

Here are the steps I took to fix it. Make sure you are logged into sync and hit the sync button to update it. This will save your bookmarks and user settings.

If you want to be able to restore your current session go into your main drive and click users, your user name, AppData, Roaming, Mozilla, Firefox, Profiles, open that folder and copy sessionstore-backups and save it to your desktop or somewhere you can remember.

After you have done that uninstall Firefox. Now restart your computer into Safe Mode.

Go into your main drive usually C on most computers and click users, your user name, AppData, Roaming. Click the Mozilla folder and delete it. Now hit the back button and click on Local. Find the Mozilla folder in there and delete it too.

You can now restart your computer and install a fresh copy of Firefox. Once it is installed you can log into sync and it will restore all your settings and bookmarks. 

If you want to restore your previous session close Firefox and make your way back to AppData, Roaming, Mozilla, Firefox, Profiles, open the new profiles folder (Example: abcd1234.default) and paste the folder you saved called sessionstore-backups in there.

You can now open Firefox and all your tabs will be there, and after a few mins all your settings and bookmarks will be restored by sync. You shouldn't have any more problems following this method. The pages no longer stop loading and it closes like it is supposed to.

Hi dedj1234, and other readers, there is an easier way to test both a clean installation of the Firefox program files and a clean settings folder, which preserves more data. The steps are listed in this post: https://support.mozilla.org/questions/1052645#answer-707600

Hey Guys,

Thanks so much for the input. I tried your suggestion dedj1234 late last night and had no problems - tried it today too for an hour or so and it worked great. Unfortunately, I've just turned my laptop on again to be greeted by the spinning connection sign and the same Profile issue. Genuinely thought we were on to someting there, I hope it works well for you and doesn't give you any further problems though!

Hi coupd, do you exit Firefox when you put your laptop to sleep? In some past versions, Firefox did poorly when waking from sleep. Not sure whether that might be a factor in Firefox 36.

If you are feeling both frustrated and adventurous, you could try Firefox 37, which is currently in beta testing. Perhaps this problem is fixed??

• Release notes: https://www.mozilla.org/firefox/37.0beta/releasenotes/
• Download: https://www.mozilla.org/firefox/beta/all/