I'm guessing there's a problem with the hard drive, especially with all the reboots (it's probably trying to fix the problems on reboot automatically..)
I'd recommend running Disk Utility and trying to fix and it and also seeing what the errors are, it might be unfixable and would require a reformat/reinstall...
You'll need to boot off another hard drive or boot from the 10.2 CD, simply put the CD in, hold reboot the machine and hold the C key as soon as you heard the chime on boot up.
Once you're on the CD you'll want to run Disk Utility, I think it's in the 'File' menu of the installer app. Verify the Disk, then repair it if there's any problems found.
-justin