Start the Task Manager (Three-finger Salute), click the Processes tab and you will find Firefox in the list. Click on End Process and you will be able to restart Firefox.

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 <br /> -------------------------- <br /> '''You need to update the following.''' The Plugin version(s) shown below was/were submitted with your question and is/are out of date. You should update to avoid known security issues with the version(s) you have installed. Click on "More system info..." to the right of your question to see what was included with your question. *Next Generation Java Plug-in 1.6.0_24 for Mozilla browsers #'''''Check your plugin versions''''' on either of the following links': #*http://www.mozilla.com/en-US/plugincheck/ #*https://www-trunk.stage.mozilla.com/en-US/plugincheck/ #*'''Note: plugin check page does not have information on all plugin versions''' #*There are plugin specific testing links available from this page: #**http://kb.mozillazine.org/Testing_plugins #'''Update the [[Java]] plugin''' to the latest version. #*Download site: http://www.oracle.com/technetwork/java/javase/downloads/index.html (Java Platform: Download JRE) #**'''''Be sure to <u>un-check the Yahoo Toolbar</u> option during the install if you do not want it installed. #*Also see "Manual Update" in this article to update from the Java Control Panel in Windows Control Panel: http://support.mozilla.com/en-US/kb/Using+the+Java+plugin+with+Firefox#Updates #* Removing old versions (if needed): http://www.java.com/en/download/faq/remove_olderversions.xml #* Remove multiple Java Console extensions (if needed): http://kb.mozillazine.org/Firefox_:_FAQs_:_Install_Java#Multiple_Java_Console_extensions #*Java Test: http://www.java.com/en/download/help/testvm.xml

Thanks. That's a good list of things to try... considering that no apps appear to be running in Task Manager's Applications, but I'll need to see what's happening in Processes because I didn't check it every time. I think you've got me pointed in the right direction.

If this helps you find a solution, #please come back and post what you found. #Also, '''''so that other users can find solutions to previously asked Firefox support questions, please take a couple of minutes to return to the forum, sign in and click "Solved" next my answer. Thanks. '''''