This was a common problem with earlier ML's. Had it in my 98 and initially in my 02. Problem is usually the glass breakage sensor which is in the trip computer assembly. There have been updates to this part over the years and the newer ones work just fine. Only way to be certain which sensor is the trigger is for a dealer to interogate the computer to see which one actually set off the alarm. Easilly fixed, not expensive and the dealer is the best be, actually the only bet.