Victor thanks for the advise
u're right, it's related to the user profile. I logged in the same machine with another user and VS2010 Beta 1 runs fine.
I deleted [C:\Users\TFSSetup\AppData\Local\Microsoft\VisualStudio\10.0\Extensions\Microsoft] content and I still have the same problem.
Also tried deleting [C:\Users\TFSSetup\AppData\Local\Microsoft\VisualStudio\10.0\Extensions] and still doesn't work.