That is called "hang at exit" and can be caused by a number of issues, including an Extension or a Plugin. Look at the following. <br /><br /> #Stop the Firefox process (you already know how to do this): #*[http://kb.mozillazine.org/Kill_application Mozillazine - Kill application] #*Windows 7 users click [http://www.techrepublic.com/blog/window-on-windows/reap-the-benefits-of-windows-7s-task-manager/2576 here] #*Mac users: http://techheavy.com/2011/02/the-mac-task-manager/ #Why Firefox may hang: #*[http://support.mozilla.com/en-US/kb/Firefox+hangs Firefox hangs] (see Hang at exit) #*[http://kb.mozillazine.org/Firefox_hangs Firefox hangs (Mozillazine)] (see Hang at exit and Closing Firefox properly) #*[https://support.mozilla.com/en-US/kb/Firefox+is+already+running+but+is+not+responding Firefox is already running but is not responding] #Use Firefox Safe Mode to find a problem with an Extension or Plugin: #*Don't check anything when entering Safe Mode, just continue #*If the problem does not occur in Safe Mode it is probably and Extension or Plugin causing the problem #*See: #**[[Safe Mode]] and [http://kb.mozillazine.org/Safe_Mode Safe Mode (Mozillazine)] #**[http://support.mozilla.com/en-US/kb/Troubleshooting+extensions+and+themes Troubleshooting extensions and themes] #**[http://support.mozilla.com/en-US/kb/Troubleshooting+plugins Troubleshooting plugins] #**[http://support.mozilla.com/en-US/kb/Basic+Troubleshooting Basic Troubleshooting] '''If this reply solves your problem, please click "Solved It" next to this reply when <u>signed-in</u> to the forum.''' ------------------------- Not related to your question, but... You need to update some plug-ins: *Plug-in check: https://www-trunk.stage.mozilla.com/en-US/plugincheck/ *Next Generation Java Plug-in for Mozilla browsers: [https://support.mozilla.com/en-US/kb/Using%20the%20Java%20plugin%20with%20Firefox#w_installing-or-updating-java Installing or Updating Java in Firefox]