BMW: BMW Windows and Locks, cell phone tower, air traffic controller

Question
Hello:

I have a 1999 BMW 323i, & I have a problem with the car staying locked.  When I lock or close the doors,  after about an hour or so, I come out to see that the windows are down, and the doors are unlocked.  Please tell me what causes this.  Thanks in advance!
DJ

Answer
Can you tell me the body style of the car. Is it e36 or e46, coupe sedan or convertable. And is the key a 3 button square remote key or a key with a seperate key fob with 2 buttons. The first 2 things that come to mind are how you use it or local interference. Even if you are 50 feet away and you press the button 2 or 3 times quickly to unlock it will open all locks and windows, maybe try not pressing the button until you are next to the car. The other thought is if the car is parked within a couple miles of an airport or hospital or even a cell phone tower sometimes you can get crossed frequencies that screw with the remote reciever and roll down the windows. I has an X5 run me ragged for days until I found out the owner was a air traffic controller at the local metro airport. If you don't use the comfort open feature of the key anyway you could just take it to the dealer and they can reset the car/key memory to not have comfort open. It would probably cost .5hr labor time but it is better than having your car open without you there. Let me know if I am way off or have the wrong model.