Crash

I have repaired a computer loaded win XP home and run constantly (36 hours) in my office. I take the computer to my customer?s home plug in turn the computer on and as if the electrical system has a virus, it wipes out the o/s and the computer does not recognize the hard drive.
This is on an electrical circuit that has an older Gateway unit running Win 98SE.

Take the computer back to the office and the hard drive is recognized and I reload Win XP without incident. This has happened numerous times. My understanding is that some time ago a network possibly for sound was run over the electrical wiring. Could this affect the unit?

Bruce Johnson