My only guess would be that there was an error in the audio file there, or an error in the extraction (did you try it more than once?). You might want to run the VOB through VOBrator, extract the audio as a WAV, and load the WAV into DVDLab Pro.
"(one that can turn DVD compliant video and audio into a DVD [VOB's + IFO's] without re-encoding like DVD Lab can)? "
Don't knock DVDLab Pro for this. I, for one, love the compliance checking. Keep in mind that you can for DVDLab Pro to *not* demux the files. You might want to try this, or even have DVDLab join the VOBs for you.