Start Firefox in Safe Mode to check if one of the extensions or if hardware acceleration is causing the problem (switch to the DEFAULT theme: Firefox/Tools > Add-ons > Appearance/Themes).

• Don't make any changes on the Safe mode start window.
• https://support.mozilla.org/kb/Safe+Mode

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

Try to remove the Firefox plist file (org.mozilla.firefox.plist).

• http://www.macfixit.com/article.php?story=20060606082246983 How .plist files become corrupt and troubleshooting the results

Go to "~/Library/Preferences" and remove the plist file for Firefox (org.mozilla.firefox.plist)

Thanks for the advice. The drop down at help is greyed out and I can't select any options. The .plst file doesn't exist

The plist file might be in a hidden location (~/Library).

Open Finder and use one of these:

• Go > Go To Folder (Shift-Command-G) and in the dialog type: ~/Library
• Open the "Go" menu and hold down the Option key to make the Library appear

• http://kb2.adobe.com/cps/909/cpsid_90947.html Access hidden user library files

You can also try to repair the disk permissions:

• http://thexlab.com/faqs/repairprocess.html

I still can't see a .plist for firefox. I don't believe I have a disk problem everything works fine except firefox. Is this version supposed to be stable with Mountain Lion 10.8?