I've been seeing similar issues on a well established system that's been running Windows 7 ultimate 32bit for nearly two years and IE9 (without issue) since day of release, that computer is my "retired" HP dc7600 that I gave to my father, who insists FF is better.
Well since installing FF.11 he has been experiencing 4-6 BSoD's daily.
Leave FF-11 closed, and browse with IE9 no problems, browse with FF and everything turns to $hit.
It's funny how many people who constantly badmouth IE (who in my opinion)
have never used a version of IE newer than 6.x can also put up with FF's browser of the week.
It reminds me of the old piece on Onion News network about "sony's stupid Fu^kin& piece of $hit that doesn't Fu^kin& work"....
Yet people line up to download the newest FF.
People who dislike IE9 because they are too stupid to realize that several necissary features are turned off by default (Favorites bar for instance) on installation will feel right at home with FF11 because it does the same damned thing.... "Tools" is turned off by Default.