new computer build, freezes and reboots

[DarkSide8416]

just built my friends new system, components are as follows:
Athlon 64 3200+
Abit KV8-MAX3
2x512 Corsair PC3200XMS Pro edition (the ones with lights)
36gb western digital raptor
160gb western digital SATA HD
geforce4 ti4200
Antec TrueBlue480 psu

After about an hour of him playing UO his computer either freezes or reboots itself. It is not overheating, it hovers between 106 and 115 fahrenheit. any suggestions would be helpful

[Fronic]

Reseat the CPU, that's all I could think of.

[Dc5e]

whats UO? i'm guessing its some game.... but if that happens, maybe the graphics card overheating?? try blowing a huge fan over the gfx card just to see if it'll eventually freeze and reboot