This does sound like

by Jimmy Greystone - 2/27/12 6:59 AM

In Reply to: Constant rebooting in XP by Kurashiki

This does sound like a heat issue, but it's more likely your CPU that's overheating than the HDD. If the HDD overheated, the system would lock up and you wouldn't be able to use it anymore, but it wouldn't cause the system to reboot. An overheating CPU could cause that, as well as an overtaxed power supply.