My panoramic roof was fixed approximately 3 years ago while under warranty for this problem in which the roof comes off the tracks and they have to replace the tracks. Now I am having the same problem and I feel it is a defect in the workmanship of Mercedes . I feel that Mercedes should fix it at no charge, but I was told it would cost about 5000.00 to fix. This is ridiculous and obviously a problem on Mercedes Benz who are at fault. It's possible it wasn't fixed right the first time and, now for their failure in there workmanship, they want me to pay to do it again. I also own a 2001 Acura 3.2 tl with a moon roof and the roof never ever gave me a problem and still works at the present time.