Has anyone had problems with the TPM system ? I have had mine into the dealership 5 times since 8/07. "Command" message "tire pressure monitor inoperative". After the forth visit they changed out the MB phone unit which eliminated that message (theory was that the "bluetooth" from the phone could be interfering), but now I am still getting a red warning to check tire pressures every once in a while. When I check the tires there is no change in actual pressure. Any thoughts ?

I have a 2008 CLK 350 convertible also with a recurring "tire pressure monitor inoperative" message. I see its been some time since you posted - did you ever find a solution?

Yes, and I believe there was a service bulletin on the issue that had to do with transmitter/receiver interference that was the root of the issue. This was determined after replacement of sensors and the reciever proved ineffective in resolving the problem. As I recall the service tech had to do a fair amount of research to get to the bottom of it.