Can't login

Have something strange here. I have a Windows XP Pro machine that
belongs to a friend of mine. The other day she could not login. I
have the ADMIN Password and I am also a user. None of my password
work.

The strangest this is the Login Screen. It look like the one you get
when you setup a machine to go login to a domain. Another strange
thing is when you hit the options button in the lower right hand
corner that only option that comes up is to shut down.

I thought the machine might have a virus so I pulled the hard drives
out and attached them my laptop and ran both Anti Virus and Anti
Spyware scans and nothing shows up.

Any Ideas?

Thanks

Ron
.