I think there may be a problem with VMC on a Vista 64-bit installation. I've noticed that the people postin in this thread with persistent problems that haven't been resolved (myself included) are running Vista 64-bit. I'm running Ultimate myself, I'm not sure if maybe that is also a common denominator.
Is anyone running a 64-bit Vista installation with VMC successfully? If anyone is, could you please tell us if you've had problems with VMC in the past, and what you did to rememdy them? Otherwise there may be a Vista 64-specific bug here.