Mitsubishi,Doors lock and Unlock when vehicle is off and parked!

My vehicles lock and unlock feature has started giving problems. When the engine is switched off and the car is parked, the lock and unlock feature keeps on activating i.e. All four door locks will lock and then unlock every few seconds and the indicator lights will also flicker as the door locks lock and unlock. This only happens when the engine is switched off. There is no problem while the vehicle is being driven but as soon as the vehicle is switched off and parked the problem starts. The vechile remote key has also stopped working i.e. I cannot lock or unlock the doors with the remote key