Our 2002 Disco equipped with DVD player is driving us batty. It often gives an "INVALID MEDIA" error after attempting to read a DVD for ~30-60 seconds. Sometimes a disc will work, sometimes not. At first, we attributed this problem to widescreen formats, then newer discs - now it is happening to most any disc. Repeated insertions sometimes does the trick. Is there any maintenance (cleaning) that we can do to remedy this problem? Is anyone else experiencing this problem? Thank you for your help and suggestions!