Like russs15, I've also got around disc corruption problems in the past by trying different drives. The other trick I've found is DVD Decrypter can be very good at dealing with hard to read discs - there are several different I/O settings for reading a disc, and some of these are more robust when attempting to read problem discs. It may take a lot of retry attempts, but its helped me recover precious seemingly corrupt discs a few times.
Just a thought.