In that case, event viewer can be used to discover the culprit.
How To Use Event Viewer - http://www.bleepingcomputer.com/forums/t/40108/how-to-use-event-viewer/
Pay attention especially to posts one and two. Later posts start dealing with the bsods.
Points 5&6 in the first post will help you to isolate the information needed to resolve your issue.
The "information" events may be filtered out using the "view" drop-down.
That way you wont' need to scroll through so much information to find the applicable event.
When you find some events that relate to the crash of Firefox, post that information
if you need more help,
and someone will be able to help you from there.