Why is Firefox continuing to run after I shut down the internet connection?

Question

I am having a problem with Firefox not shutting down. I shut down the internet, then go back on later and I get an error message that Firefox is already running and that I will need to reboot my system to clear the problem. I am running Firefox 3.6.17 on Windows Xp with sp3. I tried running Firefox 4.0 and it just did not run at all so I went back to the previous version.

Answer 1

Hanging at exit is usually caused by and Extension or Plugin.
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
** 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:
****https://support.mozilla.com/en-US/kb/Safe%20Mode
****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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