I did some looking around in teh event viewer. Everytime I had a reboot, there is an entry similiar to this:
The computer has rebooted from a bugcheck. The bugcheck was: 0x10000050 (0x86c84000, 0x00000001, 0xbfc9413c, 0x00000000). A dump was saved in: C:\WINDOWS\Minidump\Mini102705-01.dmp...