Why Parallels Desktop warns about booting from Boot Camp partition

You know how Parallels Desktop puts up this big "wet paint" warning not to interrupt a start-up from a Boot Camp partition? I learned a hard lesson about why that's there.

My Parallels Desktop took a (core) dump while it was launching Vista from a known-healthy Boot Camp partition. It's probably no surprise that subsequent attempts to repeat that process consistently met with exactly the same result.

When you ask Desktop to boot from Boot Camp, it takes a while to alter Windows' reality with regard to the hardware on which it's running. I've always admired that Desktop and VMware Fusion are able to pull off this feat without triggering Windows' licensing boobytrap. Normally, when you make some significant change to your PC's hardware, Windows forces you to reauthorize your copy of the OS.

When Parallels Desktop blew its brains out mid-boot, it not only left itself in a non-functional state, it lit the fuse on Vista's authorization bomb. When I boot directly to the Boot Camp partition, it asks me to enter my Vista product key. I haven't taken the time to do this yet, but I'm having a bet with myself about what will happen when I re-enter my Vista key. Did Vista generate a new signature reflecting Parallels Desktop's phony hardware (or the half of it that Desktop put in place before it crashed)? If so, will Vista see yet another change when it sniffs out my actual configuration and put me through this again?

Are my Apple drivers blown away? Can I just reinstall them over the Vista install that's there, or will I have to reinstall Vista?

The next time I a) get a hankering to run Vista, and b) have a spare half day to mess with it, I'll find out the answers to these burning questions. Bets, anyone?