Discovered after several fresh installs after playing with virtualization that is was blocked by webcam install..
The webcam works okay (s8850i by sonix) in 7/64 and good in skype..but stops virtualization dead till it is disabled or uninstalled.
From my experience with it so far Virtualization seems very easily disrupted.
I just seem to get over one thing and something else plays up...having real second thoughts as all these things go great in xp now.
Anyway thought this info might help someone if they find the virtualization installed ok but wont run...check by disabling drivers...webcams seem to be a real issue in the win 7 64...