Windows XP has by default in case of system crash restart.
This policy is valid if the crash was caused by transient event, but if a serious error to reboot the PC will continue indefinitely, without you seeing any messages for diagnostics.
If the system is able to boot in safe mode you can use the "classic", ie:
Start> Control Panel> System> Advanced> Startup and Recovery> Settings and from there remove the checkmark from the Automatically Restart voice
The problem is that XP will not boot even in safe mode ...
