Did you change the name of the original explorer.exe, because as far as i know when ever you login to windows explorer.exe must load to your memory if not may be you explorer.exe if crash.

as i...

Hay Matt,
I think your Windows Boot Sector is crash, so
Boot the computer using the XP CD. You may need to change the boot order in the system BIOS so the CD boots before the hard drive.
When...