MG ZR battery goes flat air flow metre makes a noise while the car is not running with no keys in the ignition also the windoors still open with the ignition on

my mg zr 1.4 starts and drives but shudders through the gears engine managment light on aswel. but wen the engine is off and the keys are out of the egnition. thers a buzzing sound coming from the air flow metre also this runs my battery flat and im sure im loosing abit of power also my electric windoors will work with no ignition switched on and ive checked my mates mg and his dont do this with no keys in the ignition any idears please ???