Aliasalpha: Test the same site in IE and see if it crashes the same way. IE's crash reports are usually a bit more informative (though I've not used FF in a fair while)
The same problem occurred once I had installed Adobe Flash. That seems to indicate the problem. When I opened multiple tabs, I got this error. IE did seem to manage to sort itself out though, in a way that Firefox hasn't managed thus far.
Problem signature:
Problem Event Name: APPCRASH
Application Name: iexplore.exe
Application Version: 8.0.6001.18828
Application Timestamp: 4a960753
Fault Module Name: StackHash_a1c8
Fault Module Version: 6.0.6002.18005
Fault Module Timestamp: 49e0421d
Exception Code: c0000374
Exception Offset: 00000000000aef37
OS Version: 6.0.6002.2.2.0.768.3
Locale ID: 2057
Additional Information 1: a1c8
Additional Information 2: cabe64b2eea259cc4dc74e6a6e84d583
Additional Information 3: 5d92
Additional Information 4: c72228ac5164fc5dd0b1714eb5290bf3