Starts up automatically?
There is one of the simple problems that I have not seen. Nobody has suggested going into the BIOS to turn off the WAKE ONLAN function. Somehow I think if you look into your BIOS and correct it there (turn it off) you will fix your problem. The problem occurs if you are on the network of a LAN, if you have this set in the BIOS.
Hope this helps
BIOS is a scary place if one does not know what they are doing.