|It probably says 'drive not ready' meaning the DVD disk isn't being accessed. |
Even though it's seeing CD's OK the DVD function may be bad. Are you having the same problem with all your DVD's?
Is it giving that message when you try to open it from 'my computer' or when you try to play a movie?
Did anything happen (hardware or software changes) between the last time it worked OK and the first time it didn't?
Ubuntu Cheeta, Ubuntu !