Firefox claims that it is already running and will not let me start a new session after closing out

Question

I've been having this problem intermittently on both my Dell XPS 8000 and my HP nx7400 laptop. The Dell is running the latest version of Windows 7 Pro and the HP is running XP Pro (fully updated). After closing out of a Firefox session and running other apps, Firefox will not let me initiate another session, saying that "Firefox is already running... Please close the session..." That's not an exact quote, but you get the idea. CTRL-ALT-DEL and all other conventional means don't work and I am forced to reboot the system. This is a royal pain.. and I need some pain relief! Any suggestions? I may revert to an earlier version of Firefox until I see a solution... can't hurt, but I really like 4.0 and I don't look at going backwards as "progress."
Thanks.
Tom

Answer 1

Sounds like it is hanging when you exit and later try to restart Firefox.
* How to stop the running Firefox process
** In Task Manager, does firefox.exe show in the '''<u>Processes</u>''' tab?
** See: http://kb.mozillazine.org/Kill_application
**Windows 7 users: http://www.techrepublic.com/blog/window-on-windows/reap-the-benefits-of-windows-7s-task-manager/2576
* What may cause Firefox to hang at exit
**Windows 7 Task Manager: http://www.techrepublic.com/blog/window-on-windows/reap-the-benefits-of-windows-7s-task-manager/2576
** http://support.mozilla.com/en-US/kb/Firefox+hangs
** http://kb.mozillazine.org/Firefox_hangs
** https://support.mozilla.com/en-US/kb/Firefox+is+already+running+but+is+not+responding
* You may need to try Firefox Safe Mode
** You may need to use '''Safe Mode''' to locate the problem:
***See: http://kb.mozillazine.org/Safe_Mode
***Firefox 4 users, hold the Shift key while clicking the Firefox 4 desktop icon to enter Safe Mode.
***Firefox Safe Mode is a diagnostic mode that disables Extensions and some other features of Firefox.
****In Firefox 4, Safe Mode also disables Plugins and Hardware Acceleration.
****If you are using a theme, switch to the DEFAULT theme: Tools > Add-ons > Themes '''<u>before</u>''' starting Safe Mode (In Firefox 4, Tools > Add-ons > Appearance). See: http://support.mozilla.com/en-US/kb/Using%20themes%20with%20Firefox#w_managing-themes-and-personas
****When entering Safe Mode, do not check any items on the entry window, just click "Continue in Safe Mode".
****Test to see if the problem you are experiencing is corrected.
*** If the problem does not occur in Safe-mode then disable all of your Extensions and Plug-ins and then try to find which is causing it
***#by enabling '''<u>one at a time</u>''' until the problem reappears.
***#You can also enable a few at a time (3-5), keeping track of what you just re-enabled to see if the problem re-occurs; this will help narrow down the possibilities if you have a large number of add-ons.
***#'''<u>You MUST close and restart Firefox after EACH change</u>''' via File > Restart Firefox (on Mac: Firefox > Quit).
***#You can use "Disable all add-ons" on the Safe Mode start window.
**See the following for more information
*** http://support.mozilla.com/en-US/kb/Troubleshooting+extensions+and+themes
*** http://support.mozilla.com/en-US/kb/Troubleshooting+plugins
*** http://support.mozilla.com/en-US/kb/Basic+Troubleshooting
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