Random rebooting

[SwatX546]

As the title says, my computer randomly reboots. Nothing in the event viewer outside of the minidumps.

It also seems to start when I'm about 15minutes into playing a round of Dawn of War 2. Regardless, I can't figure the issue out.

Help is much appreciated.

 

[Bobbye]

I don't do the minidumps, but I think some operating system and computer specs would be helpful.

Vista? Windows XP? How much RAM? Laptop or desktop?