Hello,
 Yep, I've had this happen a couple of times. I'm running Vue6,Vue6i, and Vue7c on my machine with dual boot WinXP Pro and WinXP64.

Vue, all of them, put a file called Vue----.reg in the windows folder on your boot drive and for some reason it get corrupted. When you get Vue running, make a copy of these file(s) . If it happens again, just replace them with the backups. This works for me but not sure if Vista is different or not.

Now if I can just figure out why Vue6i has started crashing on ecosystem renders 8-(

Later...

No good deed goes unpunished ...