ok i have assembled/sold something close to 1500 systems until now and never had any problems of such a manner and neither any of my customers. why?
i always use a surge protector and i give one free with any system i sell because the number one reason why a computer gets wasted is because of crazy power surges and they're not always caused by power plugs.
those people who have cable modems connected to their systems experience power surges and often burn your cpu/mobo!
so if you already have a GOOD surge protector and don't have a cable internet or cable TV on your computer, and have checked the wake on LAN options on both your motherboard bios and/or your modem off,
i suggest you call an EXORCIST to fix your problem for you!!!