At one of my recent customer engagements, I came across this particular problem where VS2010 crashed on me each time I tried to record or replay a test that was developed earlier using VS2010.
Further investigation into the causes of the crash revealed -
UPDATE 1 for VS 2012 updates the Microsoft.VisualStudio.QualityTools.WebTestFramework.dll in the GAC .
Since that version of the DLL is not compatible with VS2010, it crashes each time you want to record or replay a Webtest.
At the time of writing post, there isn't a fix available. However, MS would have a one available soon.