Re: S-1-5-21...

I would check the list of users using the NET USERS command, then try in safe mode through the UI and NET USERS, and if you still don't have a bite, try using the ntpasswd boot CD and see if it shows up with that. Failing that, back to the drawing board for another idea.

I would also check the ACLs using XCACLS (available from MS site) in various modes, and try the ACL UI in safe mode.

I apologise if I'm suggesting things you've already said you've tried, just drove ~250 miles with man-flu :)

Mike Moratz-Coppins