I am encountering a strange problem with my 2003 C320. This just started today. I drove to my kid's school, stopped the car, got out and locked the doors with the remote. Then the car alarm went off. I noticed that the passenger side front door lock did not lock. So I unlocked the car (the alarm turned off), locked the passenger door manually, locked all other doors using the remote and the alarm went off again. I was in a bit of a hurry so I pressed the unlock button on the remote and went inside. I came out an hour later the alarm was going off again. I pressed the unlock button on the remote the alarm turned off. I drove to work and the same scenario happened. Any help or advice would be greatly appreciated before I contact the dealership. The dealers around here are not the most honest.