Older Backup won't work.

What media did you use for the backup? Have you ran the Nero cd scan to see how the disk is maintaining?

Normally, the media used to record is the first culprit we think of (high quality media has better long term storage potential than lesser media). Alternately, a burner that is on its way out may be the cause of irregularities (seen as different color rings on the burned optical surface - an evenly darkened disc is the desired look). Lastly, the method of storage of the discs can definately affect the playability and longevity of the discs. Discs need to be stored out of sunlight and in a cool environment. Even storage pressure is a must (prevention of warpage)

Best media brands

!) Taiyo Yuden
2) Verbatims (preferably MIS,MIT,MIJ, not MII)
3) Sony

Both rtm and Endo are right on the money in their posts. Quality media is a must. Many people make the mistake of thinking that because they were able to burn the files initially or even that it rated a nice scan using Nero or DVDInfo Pro, that the world is right and good. Then they come along, as you have, and find that their media has degraded and hopefully not past the point of being able to salvage the files.
Have you tried reripping the files using good old DVD Decrypter alone or in conjunction with RipIt4Me? DVD Decrypter is very good at working through errors and inserting dummy files where needed. Maybe this can get you back what you have lost.

Very true, Brother Ferg. It's one of the reasons I still keep dvd decrypter around, to copy disks I already have burned.

Well the disc in question was burned on a Memorex blank disc. I'm guessing that's bad? I did try dvd decryptor and no joy. I'm guessing Ill have to rip the store bought one again?

Thanks again. You guys really know this stuff.

Well the disc in question was burned on a Memorex blank disc

'Nuff said.

Typically Memorex aren't known for being high quality. You're best bet is to abstain. Use the discs Endo mentioned earlier, and in that order.

As far as you're existing bad disc...if you can't cut through it with Dvd Decrypter/RipIt4Me - your best bet would be re-ripping your commercial version of the movie. This time, burn it on a good disc!

that sucks cuz I've got a ton of movies backed up with Memorex. Thanks for the information though. I'll rip and burn it again. I'm going out now to get some better blanks.

Verbies and Sony should be easy to come by in brick and mortars. TY's have to be purchased online. Just so you're aware.

In the United States , TY's are best purchased from (online)

1) Supermediastore.com
2) Meritline.com
3) Rima.com