Hi lman29,

Please have a look at this article: Firefox won't start - find solutions

I hope that helps. Post back if not.

--Edward

Hi Edward,

Thanks for your help, but unfortunately I tried everything on that page and nothing worked. :(

On a random other note, my iTunes stopped working at the same time as Firefox if that connection helps anyone.

Hmm. Ok if other programs are have also stopped working that makes me suspect something outside firefox causing the problem. Have you installed all the latest security patches? Not sure if the Flashback malware has been know to cause this problem: https://support.apple.com/kb/DL1534

Please also see this previous question. It looks like a similar issue to yours: https://support.mozilla.org/en-US/que.../924843

I am not sure if that was ever resolved but I think your next step should be to follow cor-el's advice and try to create a new profile to test whether firefox will start with blank profile. If it does then you can begin to migrate parts of your old profile onto the new one until you find the problem.

I'll quote cor-el's post below:

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

See "Basic Troubleshooting: Make a new profile":

   https://support.mozilla.org/kb/Basic+Troubleshooting#w_8-make-a-new-profile 

There may be extensions and plugins installed by default in a new profile, so check that in "Tools > Add-ons > Extensions & Plugins" in case there are still problems.

If that new profile works then you can transfer some files from the old profile to that new profile, but be careful not to copy corrupted files. See:

   http://kb.mozillazine.org/Transferring_data_to_a_new_profile_-_Firefox

Post back if that doesn't help.