Hi, Please check if this happens in [https://support.mozilla.com/en-US/kb/Safe%20Mode Safe Mode.] While in Safe Mode you can also try again after enabling only the Flash plugin in '''Tools''' ('''Alt''' + '''T''') > '''Add-ons''' > '''Plugins'''. [https://support.mozilla.com/en-US/kb/Troubleshooting%20plugins Troubleshooting Plugins] [http://kb.mozillazine.org/Testing_plugins Testing Plugins]

You can also try to disable the hardware acceleration in the Flash Player. See: * https://support.mozilla.org/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://kb.mozillazine.org/Plugin-container_and_out-of-process_plugins