My Laguna II 1.9dci is suffering from loss of electrical power while the engine is off. It happens at random intervals. If the car alarm is alarmed, while the car is suffering from power loss, the car cannot be unlocked. The alarm LED on the dashboard fails to flash. At intervals of 1-2 minutes the right indicator light will briefly flicker. This is the only time the car will respond to an unlock/disarm request. I have had the car with the main dealer twice who say they cannot find any problems?? If I leave the car disarmed and come back later and open the door, the interior\door lights do not come on as well suggesting the problem is generally with the car electrics. I have been told the battery is ok. Once the car has been disarmed or the car detects that the interior lights should be on after a couple of minutes, the car then works fine. Has anyone else suffered from this problem or have any idea how to fix it?