Boot the computer in Windows Safe Mode with network support (press F8 on the boot screen) as a test. *http://www.bleepingcomputer.com/tutorials/how-to-start-windows-in-safe-mode/ You can try to disable hardware acceleration in Firefox. *Tools > Options > Advanced > General > Browsing: "Use hardware acceleration when available" You need to close and restart Firefox after toggling this setting. *https://support.mozilla.org/kb/Troubleshooting+extensions+and+themes *https://support.mozilla.org/kb/upgrade-graphics-drivers-use-hardware-acceleration 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

cor-el, I downgraded back to Firefox 31 and this problem doesn't happen there. I think you should get Mozilla to fix this problem for Firefox 33. This is the problem I was having with Firefox 32.