power problems?

This is mainly a question. I have a client that is having what appears to be power loss. Not off/on type power loss but that the system itself is not getting enough power from the wall outlet. I have tried 3 different systems, different configurations and the same errors occur. Email locking is the first sign and then he looses time..but only if the computer is on. If he reboots the time is correct. Anyone got any suggestions as to how I can possibly resolve this short of rewiring the guys house?