Another shot in the dark.... Borrow or buy a receptacle checker and check every outlet in your home for correct polarity. If even one is reversed it could be sending voltage to the neutral side of your house wiring and may be an easy issue to fix once found. The equipment plugged in is expecting 120 vac on the hot side of the receptacle (the smaller slot)and ground on the larger slot. If one of the wires in the house is reversed then you could be generating a voltage on the neutral lead. Essentially you could find it by reading the voltage witha multimeter, between the larger slot and the ground. There should be no voltage. If there is voltage one of the hot wires is connected to the neutral somewhere in your house. If any recent wiring was done I would start there.