As your Firefox crashes even in Safe Mode, it is not being caused by an extension, theme or hardware acceleration. [https://support.mozilla.com/en-US/kb/Firefox%20crashes#w_get-help-fixing-this-crash Try to get help with your crash ID.] Another option would be to completely uninstall it and install it again.

Your crashreport:<br> https://crash-stats.mozilla.com/report/index/bp-f653c7f4-4250-4aa6-a898-675f92111105<br> Firefox 7.0.1 Crash Report [@ _purecall | nsXPTCStubBase::QueryInterface(nsID const&, void**) ] <br> This is caused by [http://www.trusteer.com/product/trusteer-rapport Trusteer Rapport]. Try to disable it and see if that stops the crashing.<br> You can stop Rapport using Start Menu > Programs > Trusteer Rapport > Stop Rapport<br> You can ask their helpdesk when an updated version of their product will be made available or, if you don't need this software, uninstall it.<br> http://www.trusteer.com/support/en/report-problem<br> According to the user in question [http://support.mozilla.com/nl/questions/892517 892517] Trusteer is aware of the problem and working on a fix.<br> See also [https://bugzilla.mozilla.org/show_bug.cgi?id=699776 Bug 699776] - crash in nsXPTCStubBase::QueryInterface involving RapportTanzan7.dll in the stack.