I had Visual Studio 2010 Beta 2 installed and running for a few weeks, and then suddenly, it started crashing every time I tried to start it. I uninstalled, re-installed, etc., but the problem turned out to be a font viewer program I had installed. For some reason, the date-time modified of some random ttf file in the Windows Fonts folder had gotten changed.
Microsoft has a workaround posted at https://connect.microsoft.com/VisualStudio/feedback/ViewFeedback.aspx?FeedbackID=509285&wa=wsignin1.0#tabs . I downloaded a freeware program called "FileTouch" from http://wareseeker.com/download/filetouch-1.0.rar/5f214be45. After I opened a DOS window, navigated to the %windir%\Fonts folder, and ran "FileTouch wingdng3.ttf", Visual Studio 2010 Beta 2 started up with no problems.