After installing XP SP3 and rebooting, the system may go into a reboot loop. In order to see the stop error, you must boot using the F8 key and choose the option "Disable automatic restart on a serious error". After this the computer blue screens with the following error:
STOP: 0x0000007E (0xc0000005, 0xB9C3C756, 0xBA4EB42C, 0xBA4EB128)
The sub codes above (in the parentheses) may be different.