I was thinking that myself. It'd be easy enough to test for, run the comp with the side off (in a reasonably cool room), if it still locks, it's likely to be a power supply issue.
I am with everyone else, you system is over heating.
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Creator of the Star Trek Mod - AST Mod - 78 Ship Sets - Conquest Mod - Atrocities Star Wars Mod - Galaxy Reborn Mod - and Subterfuge Mod.