Ok I need some help, I have the same inverter charger in my 2004 Vectra. We have been stationary for 6 months hooked to shore power. We unhooked and headed down the road we are getting buzzing through the stereo speakers. If we are parked and the motor is turned of and the speaker switch is turned to the engine it won't buzz. When the motor is running no matter where we have the switch turned to it buzzes. I am thinking maybe the inverter is crap! Help!