Hey,
I use a combination of AnyDVD and Nero Recode to back up my DVD's. Until recently(when i tried to play one of em) i noticed that the Menu's/Extra featues didn't have sound at all. And most of the movies i was backing up didn't have complete sound. Even if i backup an unprotected DVD
After a long while of trial and errors, I realized that whatever audio in 2 channel doesn't decode/encode. For a movie that has 2-channel, When i preview the video in Nero digital with 5.1 dobly it plays fine, but immediately i change the preview sound to 2-channel the sound goes off, and the video becomes a little slower at playing.
Most Menu's and extra features are in 2-channel, even some movies are in 2-channel, and theres no way i can get recode to work with it.
When i purchased my serial, they said dobly digital encoding/decoding was included, i also have the DVD plug in serial. I even got a pure Multichannel plugin serial from a friend and it still made no difference. I've uninstalled and reinstalled several times over using the Nero clean tool and nothing seems to work.

What to do now???????????

Best to talk to Ahead about the problem. In trying to stem the use of illegal serials a proper install has become more diffiicult. Using the various plug-in packs packs/serials floating around seldom seems to work. Unauthorized serials seem to logged in various parts of the registry, seems Nero checks all these spots.

Get DVDShrink (free), basically the same results without worrying about plug-ins.