I saw a similar thread on a different forum where the user traced it to an "Xinha" add-on. Does that sound familiar? http://forums.mozillazine.org/viewtopic.php?f=38&t=2996501 If not, could you test in Firefox's Safe Mode? In Safe Mode, Firefox temporarily deactivates extensions, hardware acceleration, and some other advanced features to help you assess whether these are causing the problem. ''If Firefox is not running:'' Hold down the Shift key when starting Firefox. ''If Firefox is running:'' You can restart Firefox in Safe Mode using either: * "3-bar" menu button > "?" button > Restart with Add-ons Disabled * Help menu > Restart with Add-ons Disabled and OK the restart. ''Both scenarios:'' A small dialog should appear. Click "Start in Safe Mode" (''not'' Refresh). Any improvement? (More info: [[Troubleshoot Firefox issues using Safe Mode]])