Hi there, looking for some advice

My step daughter has forgotten her password (I am the administrator and she has been set up as one of the users). We do not have a password disk for her.

I have reset her password using my administrator account (using Manage another account). This seems to have worked ok but when my daughter tries to log in it accepts the password but then logs off. I've rebooted the lap top a couple of times but it hasn't made any difference. I tried to set up a guest account as a test and even though it doesn't have a password it looks like its going to let you and and then logs off. I think I had a similar problem when I set up the account four years ago but I can't remember how I got it work but I seem to feel it was something simple.

Any ideas?