Domain user disappears.
windows 7 laptop
exchange server for emails
A teacher complained that she could not login to her laptop. I checked the AD to find her user, and it had disappeared.
I re-created her as a user on the domain.
I asked her to login on her laptop and everything was fine.
10 minutes later the same thing happened again???
Have you got more than 1 domain controller, there could be a syncing error?
It could be the result of any number of things happening, but there will more than likely be some clues about what's going on in the event viewer logs of your domain controller(s).
That's where I'd be starting my troubleshooting from ...