Computer Problem - I have two Window XPs on 1 Computer, and a Drive Disappeared

This morning, my mom’s computer wouldn’t load properly. When turned on, it would start as normal, however, it then proceeded to a “Windows did not start properly” screen. It then offered several choices:

Safe Mode
Safe Mode with Networking
Safe Mode with Command Prompt

Last Known Good Configuration

Star Windows Normally

Regardless of what option we chose, the computer would go to the Windows loading screen (for all intents and purposes, it looked like it was running fine) but then after the loading screen disappeares, the computer would restart to the Gateway splash screen, then finally back to the “Windows did not start properly,” thus continuing the cycle.

At this point, I had to go to school, so my dad took over. He apparently tried to reinstall Windows, which apparenty worked, to some extend. Now when we start up the computer, we’re presented with a screen that says “Please Select the Operating System to start,” we’re then given the following two options:

Microsoft Windows XP Home Edition
Microsoft Windows XP Home Edition

Yup, the same damn OS. Anyways, the top one works fine. It’ll load windows and everything’s honkey dorey, however, the second one causes the same problem as outlined above.

Alright, so getting back to the first one that works. When I went to My Computer to check on the hard drive, our D drive is no longer listed, which was the second partitioned part of the hard drive that the computer shipped with. The C drive also lists a total size of 37 gigs, though I don’t know whether that represents the full HD’s space or not (I thought it was 80gigs, but I’m not certain). So that means that either both C & D drives are now just C, or my D drive just disappeared.

So two questions: Can I get rid of that second “Microsoft Windows XP Home Edition” so the computer just starts normally as it used to, and how can I find out if a drive is missing?

Thanks!