A. Check to see if your friend's computer is overclocked. If it is, take it down to default settings/increase cooling, and see if this fixes the problem.
B. If not A, check to see if your friend's computer has both 1. a motherboard manufacturered by Epox, AND 2. a power supply manufactured by Enermax. If yes, replace one or the other, and your problem should be solved (recommend replacement: motherboard).
B1. In the alternative, if you find both an Epox and an enermax, and are handy with a soldering iron, there may be a way to correct it, but I do not recommend that you try (see amdmb forums and search for enermax in the epox thread).
C. If none of these apply, check your power connections, check to see that the heatsink is properly mounted on the processor with thermal compound, and see that the case is properly ventilated.
Good luck,
Nack