Robbi,
There is one (maybe two) more things it could be. The PT is equipped with an RKEM (
Remote Keyless Entry Module) that's located behind the center dash (see picture). This module controls the opening of the doors and hatch. If your right about being sure that you close the hatch and you can hear it pop open when you start the car.....something could be wrong with that module so it's getting a signal to open the hatch when the ignition is turned on. Either that or maybe your hand held key fob has something wrong with it and is also the cause of the hatch opening up, BUT, the key fob would also send a signal for all the doors to open up also...unless the doors are already open (unlocked) and only the hatch opens up. [:I]
