A number of different viruses and spyware are known to crash Firefox. To ensure that your system clean of spyware and viruses, install, update their virus databases, and use both of these programs:
For more information, see:
I was working on allizom and wanted to incorporate information from this page into a new one. In the process I accidentally renamed this article instead of the one on allizom. I'm going to leave this for now as it will probably be the production version of the allizom page.