what kind of error messages do you receive while ripping (please pose full exact messages from both the anydvd ripper and form dvd decrypter)
do the errors come at the same point on the disc every time you try to rip?
do you have naother drive to try it in...some drives are better readers than others.
have you tried cleaning the disk?
set the drive speed control in anydvd to slow and quiet and try the anydvd ripper. if that doesn't work, leave anydvd open so the drive speed control is still in effect and try dvd decrypter.
it is an old movie, but did you re cently purchase it? you may be able to exchange it if your copy is defective. If it's an old copy you had sitting around you may be SOL.