Twice now, after I installed a new alarm /siren unit which I got from Mercedes dealer. the alarm has sounded while the car was parked and locked. Using the remote, I unlocked it and then locked it and the alarm stopped. I asked the serviceman at my Chrysler dealer and he told me it might be a defective door switch. Has anyone else experienced this and how did you fix it? Thank you. Mine is a 2005 coupe with 60,000 miles.