Crash ID report : 6f513c4b-e818-486c-922e-4fae02111107

Signature : _purecall | nsXPTCStubBase::QueryInterface(nsID const&, void**

Trusteer Rapport software is the problem, see also my comment in /questions/893296

Thank you so much John99, I've uninstall rapport and my FF is now back on, thanks a bunch and countinue with the good work, cheers.

Glad to have helped, and thanks for posting back to confirm that was the problem

Note the other post includes info on disabling Trusteer if you need to re-install a problematic version for occasional use. (Not much help of course if it crashes Firefox - it may work on 3.6, or try on IE)