Start Firefox in Safe Mode 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
• Do NOT click the Reset button on the Safe Mode start window

• https://support.mozilla.org/kb/Safe+Mode
• https://support.mozilla.org/kb/Troubleshooting+extensions+and+themes

Ok. I entered safe mode, the problem is gone. But I cant use my add ons now, and I have a few important ones i need to use,

Go to your add-ons page and disable some of your add-ons. Then restart. If there is still a problem, disable more of them. Once the problem is gone, you will know what group the problem is in.

Also;

Press the <Alt> or <F10> key to bring up the tool bar.. Then Tools > Options > Advanced > General. Look for and turn off Use Hardware Acceleration. Then restart.

And/or, if you can relay the error message in more detail, perhaps it will track down the culprit.

If the details are hard to capture and type, you could grab a screen shot. Please delete any confidential information from the image before posting.

This article might help: How do I create a screenshot of my problem?