[jackweirdy]

I had the horrifying experience of doing this with Windows Vista. It was at the point where XP's Hardware Abstraction Layer had been depreciated, but there wasn't any documentation for what to use instead. It was really messy. Every time I booted in a VM it thought it was an unlicensed copy, but when I booted from the physical machine it didn't see any problems. I still have no idea what caused that.

[trentmb]

I'm going to guess that Windows Activation saw a different hardware config under the VM, so it thought it was running on a completely different machine.