I own a 2006 Dodge Ram 3500 4X4 5. 9 Cummins Diesel, my problem is the Navigation Radio. The Navigation DVD is giving me a message “Disk Error”. The book that came with the truck says that no cleaner can be used. I’ve wiped off any dust on the DVD and there are no scratches on DVD. I know of two other people that have this same Navigation Radio. They are having the same problem, we were wondering if there could be any date stamp message on the DVD to make this happen. All of our units stopped on the same date. Are there other people with this same Navigation Radio having the same problems? Any Comments ?