Chances are, the install program checks the registry which did not get cleaned up. That's about the kind of performance I expect from an OS the prints two scary warnings with default cancels for "unsigned" and non "XP compatibility tagged" hardware drivers.
TechTV, recently, and PC magazine (september 3 2002) tout M$'s "compatibility mode" for XP. Try it out and let us all know how bad if fails. I hate Microsoft.
