http://forum.parallels.com/thread12395.html Can't activate in Parallels even though the partition starts fine with Boot Camp.. the problem started in the Beta.. If no solutions are proposed I'm going to try nuking the partition and re-installing.
I've been having the same problem I believe. I have Vista Ultimate installed via Boot Camp and it's purring along nicely. However, when I start up Parallels using the Boot Camp drive, it will fire up briefly, then the VM stops and the Boot Camp volume remounts in the Finder. I'm running build 4128. B