THis may help some. I've found a few DVD's that, when ripped and then processed with DVD2AVI, the audio is off right from the start. TWISTER was one DVD like this. It looks like its something in the header or pre-starting of the DVD. When ripped, you may have other stuff, like warnings or editional opening credits. I was using TMPGEnc to edit out this pre-movie stuff, but the audio was still off. I started cutting the pre-movie vob stuff in DVD2AVI, when processing it. That did it! The sync, at least with this problem, is solved. The entire resulting mpeg will be in sync. Other DVD's I found with strange sync problems, that had to be handled special were:
NUTS
A CHRISTMAS CAROL
TWISTER
(so far)...