Create a new profile as a test to check if your current profile is causing the problems. See "Basic Troubleshooting: Make a new profile": * https://support.mozilla.com/kb/Basic+Troubleshooting#w_8-make-a-new-profile There may be extensions and plugins installed by default in a new profile, so check that in "Tools > Add-ons > Extensions & Plugins" in case there are still problems. If that new profile works then you can transfer some files from the old profile to that new profile, but be careful not to copy corrupted files. See: * http://kb.mozillazine.org/Transferring_data_to_a_new_profile_-_Firefox See: * http://kb.mozillazine.org/Firefox_crashes * https://support.mozilla.com/kb/Firefox+crashes

That is a problem with the Flash 11.2.202.18 plugin that you seem to have disabled as it isn't in your More system details list. ---- Clear the Flash cookies (LSO) and settings. Flash Website Storage Settings panel: * http://www.macromedia.com/support/documentation/en/flashplayer/help/settings_manager07.html Global Storage Settings Panel: * http://www.macromedia.com/support/documentation/en/flashplayer/help/settings_manager03.html Flash Local storage settings Help: * http://www.macromedia.com/support/documentation/en/flashplayer/help/help02.html ---- Try to disable the hardware acceleration in the Flash Player. See: * https://support.mozilla.com/kb/Cannot+view+full+screen+Flash+videos * http://www.youtube.com/swf_test.html (right-click the player: Settings) Flash "Display settings" window: * http://www.macromedia.com/support/documentation/en/flashplayer/help/help01.html ---- See also: * http://kb2.adobe.com/cps/409/kb409116.html (Troubleshoot, report Flash Player video playback issues)