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).

To Enable SafeMode

• You can open Firefox 4.0+ in Safe Mode by holding the Shift key when you open the Firefox desktop or Start menu shortcut.
• Or open the Help menu and click on the Restart with Add-ons Disabled... menu item while Firefox is running.

Once you get the pop-up, just select "'Start in Safe Mode"

If it works in Safe Mode and in normal mode with all extensions (Tools > Add-ons > Extensions) disabled then try to find which extension is causing it by enabling one extension at a time until the problem reappears.

Close and restart Firefox after each change via "Firefox > Exit" (Windows: Firefox/File > Exit; Mac: "Firefox > Quit Firefox"; Linux: "Firefox/File > Quit")

• https://support.mozilla.org/en-US/kb/troubleshoot-firefox-issues-using-safe-mode
• https://support.mozilla.org/kb/Safe+Mode
• https://support.mozilla.org/kb/Troubleshooting+extensions+and+themes

I cant even get to safe mode; I get the crash reporter even with the shift key down and never even get the safe mode window. Thunderbird did the same thing when it updated last also and ended up reinstalling an older version. Even that crashed until I reverted the profile from Time Machine so whatever screws up even effects the profile. I had to go back to Chrome for now...Just to be clear - It crashed the instant you click on the icon even before the dock icon bounces. The crash reporter comes up instantly.

Create a new profile as a test to check if your current profile is causing the problems. See "Creating a profile":

• https://support.mozilla.org/kb/profile-manager-create-and-remove-firefox-profiles
• http://kb.mozillazine.org/Standard_diagnostic_-_Firefox#Profile_issues

Profile Backup and Restore

• http://kb.mozillazine.org/Profile_backup
• https://support.mozilla.org/en-US/kb/back-and-restore-information-firefox-profiles
• http://kb.mozillazine.org/Transferring_data_to_a_new_profile_-_Firefox

Trying to launch the profile program from terminal also results in the firefox crash reporter. I also ran disk utility disk repair and rebooted etc and no change.

I tried deleting the profile and moving an old profile from Time Machine. Still crashes the same. Tried deleting Firefox AND the profile and reinstalling it from scratch. Still crashes the same. Deleted Firefox again and put the previous version and its profile back from Time Machine. Works fine. Turned off auto updates. Will not update until I am convinced the problem is fixed the new version has. Problem seems the same as the latest Thunderbird which crashes the same way. Had to revert to previous version there also.