Half way through a trip my RNS-e suddenly decided to declare my nav DVD 'unreadable' (at this point I should declare that it's a copy that came with the ebay'd unit). Thinking it might be the disc I ordered a 2010 replacement (from JohnS3) and normal service resumed. Today the RNS-e declared the disc 'unreadable' again - about an hour into a trip. When I took the disc out it was pretty hot. Numerous attempts to get the RNS-e to read it failed, with the same error every time. When I got back in the car several hours later it worked fine. Then, sure enough, a hour or so into the trip home...disc 'unreadable' and the nav gives up. CDs however still play perfectly and always have done. And every other aspect of the unit works fine. Help!