Forum:Computer freezes after some time

After playing Borderlands for while (hour tops), whole computer freezes and i have to force restart.

No info found from google, most of the links said it's an heat issue, which i doubt since it has run perfectly fine before, and according to speedfan & CCC the temps are 60-65 at max.

Specs:


 * Windows Vista 64bit


 * E2200 @ 2.45GHz OC (Original 2.2GHz)


 * HD 4870 Club 3D factory OC


 * 4GB Ram