Try disabling Firefox's use of hardware graphics acceleration. So you can read the dialog, you'll need to do this in Firefox's safe mode.

orange Firefox button (or Tools menu) > Options > Advanced

On the "General" mini-tab, uncheck the box for "Use hardware acceleration when available"

Then exit and restart Firefox in normal mode. Any improvement?

This issue happens to me every once and I while, but not every time I open it up.
I just close the window and reopen it.

Does the problem occur when you run Firefox in Safe Mode?

Firefox Safe Mode

thanks to both of you.

Whiz, this has been an ongoing issue and no amount of closing/reopening browsers fixed my issue.

jscher2000, this worked! Until I shut down my computer for the evening and turned it back on this morning. The setting seemed to have reverted back to being enabled, the browser didn't remember my setting change. Any suggestions?

Hi silverwinged, the following article has some suggestions on tracking down external causes for losing your settings: How to fix preferences that won't save. It might take some time to know whether you've found the culprit.

If you notice any other data missing, consider whether you using any "cleaning" programs such as CCleaner. In that case, you might need to make an exception for Firefox or your Firefox profile folder. (You can get the path of your Firefox profile folder if you open it using Help > Troubleshooting Information > "Show Folder" button.)

If you do not keep changes after a restart or otherwise have problems with preferences, see:

• http://kb.mozillazine.org/Preferences_not_saved