Weird but I'm starting a new project and I burnt a buch of dvd's for it, taken from VHS, I renamed the vob's mpegs...when I play them in media player they are fine but when I preview or pull them into Vegas, 5 or 6, there is no audio.
What did you use to burn the DVDs? Were they finalized? Do you get picture and no sound? Have you registered MPEG pro 1 & 2? If not, try changing the file extention back to .vob (though I'm not sure that makes a difference) and register when prompted.