I noticed this problem on my crossfire about a week ago. I have 1,000 miles on the car. It's a rattling noise either in the door or where the seatbelt retracts on the drivers side. It was buggin the hell out of me because the car feels like it's built out of concrete otherwise. The funny thing is the last few days I've driven it there has been no sound even over bumpy roads. Hopefully if enough owners have this same problem they'll have a better idea how to fix it.