I had him as a limited user acc't. That's what scalds me. Someone, somewhere told him to download a program and it set him as an admin. I know he didnt do it maliciously, or break my personal password (or he'd be on my machine too) but It still irritates me to no end.
I think I may let him play with Linux for a while and then set new passwords if he hasn't destroyed it. He already knows more than I do about it. He said he wishes he had it back as windows, but I can see he's having fun with learning something new too.