It's getting more weird. Every now and then my PC would restart. But I've noticed it needs some sort of trigger; i.e. launching a certain program. For example, I click the MS Word shortcut in my start menu and it reboots. After the reboot, I find the shortcut to Word doesn't work anymore!

BTW, can you tell please tell me if I can rule out any suspects (hardware)? I have a 5-day Christmas holiday coming up, so I'd like to take this opportunity to find the trouble maker