It maybe that the motor has got stuck (they sometimes do this). What happens is that it gets jammed ON (either up or down) and then this overheats the motor and trips it out. It will then keep tripping out, colling down, tripping out whenever the car is turned on and will give the impression that the window is broken. You can tell if it is this by listening to the door and if you can hear the motor humming (no particular tune ) when you first turn the ignition on, it is stuck. Is a right pain if it sticks down .