I had a problem with my Parallels, if anyone can shed any light on it.
I installed the copy of Windows that came with my windows laptop, used the Product Key for that. All installed fine until I had to verify it. Had to install an SP2 crack to get around the verification issue, but after 30 days of it being installed, when I logged on I got a message saying that I needed to verify Windows. When I pressed OK to verify, it told me that I had already verified the windows I was running and then proceeded to log me out. When I logged back in again, took me back to that same "you need to verify windows" screen. Press OK > already verified > log out etc.
The only thing I could think of was that I used an SP2 crack on an SP1 version of windows, but as it worked for 30 days I thought nothing of it.