Start Firefox in [https://support.mozilla.org/en-US/kb/troubleshoot-firefox-issues-using-safe-mode Safe Mode to Troubleshoot the issue] and to check if one of the extensions (Firefox/Tools > Add-ons > Extensions) or if hardware acceleration is causing the problem (switch to the DEFAULT theme: Firefox/Tools > Add-ons > Appearance). * https://support.mozilla.org/en-US/kb/troubleshoot-firefox-issues-using-safe-mode *https://support.mozilla.org/kb/Safe+Mode *https://support.mozilla.org/kb/Troubleshooting+extensions+and+themes

Try to set the Flash plug to click-to-play by setting the permissions for Flash to "Ask To Activate" in "Firefox/Tools > Add-ons > Plugins". That way you can activate the Flash plugin when you need it via the Lego block icon on the location bar. Also please update the Flash plugin to the latest version. You can find the latest Flash player versions for Firefox on this page: *http://www.adobe.com/special/products/flashplayer/fp_distribution3.html *http://helpx.adobe.com/flash-player.html ---- You can check for problems with current Shockwave Flash plugin versions and try this: *check for updates for your graphics drive drivers<br>https://support.mozilla.org/kb/upgrade-graphics-drivers-use-hardware-acceleration *disable protected mode in the Flash plugin (Flash 11.3+ on Windows Vista and later) *disable hardware acceleration in the Flash plugin See also: *http://kb.mozillazine.org/Flash#Troubleshooting