Th car has 'locked itself' intermittently since I first bought it. Not sure of the date or mileage, but I believe I got it in the summer or fall of 2006 and I have no idea what the mileage was when it first happened.

If I leave my car unlocked, it will lock itself. this has happened several times, but this weekend, I knew it wasn't my imagination. I was out in my yard and the keys were inside the house (I live alone, so nobody touched the keys). I heard the car beep as if it was being locked/unlocked. sure enough, the car locked itself. Again, the dealer can't get it to do this so I don't how to resolve it. the car is still under warranty.