limited access mode

Hi All,

I searched for my problem but couldn't exactly find the answer so here's the
question. My friend bought a HP laptop with Vista Home Premium installed few
months ago. Couple days ago he bought a new USB Hard drive also from HP and
tried to attach to his laptop. At which point it crapped out on him. Not
exactly sure what happened but he ended up with his C drive renamed to Z. The
hard disk shows in Vista as unknown.

Other issues -
1. After he successfully logs in, a short menu comes up with entries like
'Go to Task Manager', 'command prompt' etc. From here he can click Task
manager and run Explorer and see the icons.
2. Most services are in stopped mode and Vista doesn't allow restarting.
3. There are no System restore points so this is not an option either.
4. The machine runs very slow.

If anybody has any clues please let me know.
Thanks in advance.

- Dan