entire C: drive is hidden

I’m helping a new user get familiar with a computer running Windows XP (unsure of home or pro) and when I went to My computer, via start menu, the entire drive is shown as a hidden folder.They have had several problems for which they called Dell, and have told me they reformatted the drive at least once. Right clicking on it gets me a limited info window that just list drives, not sound card, modem, etc.
I think this is in a user account, but I’ve tried to create a user account on my machine and hide the entire drive, and I can’t do it. What happened? How do I get around it?