I also have this problem on my '04 Coupe. Must be a defect in the design. The rattle only occurs on the passenger side, so I am not as concerned because driving the car is not about the passenger. I have tried to put the window down and I still find the "creaking" sound. I have had the dealer look at the door and they did fix it for a while, but it came back. I am in the Northeast and I notice that the creaking sound is louder in cooler weather, which may refer to the extra stiffness found in the door assemply during the colder months. I am not sure if it is rubber related and would like to think that the window is just rubbing against the metal as was mentioned in the last reply. Any further comments or an absolute fix would be most appreciated.