Crashes or other problems with certain multimedia content in Firefox (such as Youtube videos and Flash animations or games) can often be resolved by performing the steps in these Knowledge Base articles: * [[Flash Plugin - Keep it up to date and troubleshoot problems]] * [[Flash 11.3 crashes]] * [[Flash 11.3 doesn't load video in Firefox]] On Windows Vista and above, you can disable Flash protected mode by following the instructions on these pages: * http://forums.adobe.com/thread/1018071#TemporaryWorkaround * http://kb.mozillazine.org/Flash#Disabling_Protected_Mode_in_Flash_11.3 (See [http://blogs.adobe.com/asset/2012/06/inside-flash-player-protected-mode-for-firefox.html this Adobe blog post] for technical details about Flash protected mode.) Please tell us if this helped!

See: *"Hang at exit": http://kb.mozillazine.org/Firefox_hangs *"Firefox hangs when you quit it": https://support.mozilla.org/kb/Firefox+hangs Use "Firefox > Exit" (Windows: Firefox/File > Exit; Mac: Firefox > Quit Firefox; Linux: Firefox/File > Quit) to close Firefox if you are currently doing that by clicking the close X on the Firefox title bar. ----- *http://kb.mozillazine.org/Profile_in_use *https://support.mozilla.org/kb/Firefox+is+already+running+but+is+not+responding

I had the same issue as well and I fixed it by running Firefox.exe as an administrator.