If you have submitted Breakpad crash reports then post the IDs of one or more Breakpad crash reports (bp-xxxxxxxx-xxxxxxxxx-xxxx-xxxxxxxxxxxx).
You can find the IDs of the submitted crash reports on the about:crashes page.
You can open the about:crashes page via the location bar, like you open a website.

• http://kb.mozillazine.org/Breakpad (Mozilla Crash Reporter)
• https://support.mozilla.com/kb/Mozilla+Crash+Reporter
• https://developer.mozilla.org/en/How_to_get_a_stacktrace_for_a_bug_report

[08/15/09 15:15:56] Crash report submission failed: The operation completed successfully. [08/27/09 21:38:52] Crash report submitted successfully [09/26/09 02:16:24] Crash report submitted successfully [10/26/09 20:25:54] Crash report submitted successfully [02/25/10 12:52:21] Crash report submitted successfully [03/26/10 00:37:43] Crash report submitted successfully [10/02/10 20:21:38] Crash report submitted successfully [11/02/10 12:49:02] Crash report submitted successfully [12/10/10 20:26:29] Crash report submitted successfully [01/25/11 12:00:50] Crash report submitted successfully [01/25/11 12:17:23] Crash report submitted successfully [01/26/11 11:30:27] Crash report submitted successfully [03/03/11 22:47:10] Crash report submitted successfully [03/30/11 18:02:56] Crash report submitted successfully [05/26/11 18:40:07] Crash report submitted successfully [11/03/11 22:32:14] Crash report submitted successfully [11/03/11 22:33:18] Crash report submitted successfully [11/03/11 22:47:07] Crash report submitted successfully [11/03/11 22:47:27] Crash report submitted successfully [11/03/11 22:53:24] Crash report submitted successfully [11/04/11 10:40:22] Crash report submitted successfully [11/04/11 10:40:52] Crash report submitted successfully [11/04/11 10:42:02] Crash report submitted successfully [11/04/11 10:42:48] Crash report submitted successfully [11/04/11 17:13:18] Crash report submitted successfully [11/04/11 17:18:17] Crash report submitted successfully [11/04/11 17:18:55] Crash report submitted successfully [11/04/11 18:26:24] Crash report submitted successfully [11/04/11 18:26:52] Crash report submitted successfully [11/04/11 18:27:44] Crash report submitted successfully [11/04/11 18:28:03] Crash report submitted successfully [11/04/11 19:01:11] Crash report submitted successfully [11/06/11 09:31:21] Crash report submitted successfully [11/06/11 10:43:15] Crash report submitted successfully

Crash ID: bp-ec838adf-29a0-4808-bd6d-7e9e32111104

Your crashreport:
https://crash-stats.mozilla.com/report/index/bp-ec838adf-29a0-4808-bd6d-7e9e32111104
Firefox 7.0.1 Crash Report [@ _purecall | nsXPTCStubBase::QueryInterface(nsID const&, void**) ]
This is caused by Trusteer Rapport. Try to disable it and see if that stops the crashing.
You can stop Rapport using Start Menu > Programs > Trusteer Rapport > Stop Rapport
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.
http://www.trusteer.com/support/en/report-problem
According to the user in question 892517 Trusteer is aware of the problem and working on a fix.
See also Bug 699776 - crash in nsXPTCStubBase::QueryInterface involving RapportTanzan7.dll in the stack.

Does stopping Truster Rapport allow you to open Firefox without it crashing? (See above). You can stop Rapport using Start Menu > Programs > Trusteer Rapport > Stop Rapport

thank you it now works