hi yacobcajee, based on a lot of recent reports by other mac os x users, i'm just going to guess, that this might be caused by trusteer rapport. if you're a user of that program, please see if there's an update available for it or else keep it stopped/uninstalled for the moment.

https://trusteer.secure.force.com/PKB/articles/en_US/FAQ/Browser-wont-start/

yacobcajee said

Hello. I’ve been using Firefox ever since Mackeeper infiltrated Safari, but Firefox suddenly crashed this morning and won’t open. Help!!!!

Thank you for your help, Philipp. All sorted now.