DVD authoring ac3 out of sync after authoring but not before

[Genaugmen]

Before you go into how this question has been answered, please understand my situation. I have an avi with a frame rate of 25.6. I converted frame rate with virtualdubmod to 25fps. Resulting avi had no sync issues with audio. I extracted audio(mp3 48khz) to .wav and converted to ac3 with sony vegas (and also with besweet through ac3 machine gui) The audio in this avi goes silent at about 1:56:28 in the avi and demuxed mp3, as well as the .wav and final ac3, until the end of the video which is about another 90 seconds or so. Understand that the audio doesn't end at 1:56:28, it is just silence for the remaining 2 minutes or so of video. Encoding video with cce being frame-served with avisynth at 25fps and using dgpulldown to convert the mpv to 29.97fps. But when I author the dvd with these files the audio is reaching the point that it goes silent around 1:56:00-1:56:02, depending on the authoring program I use (dvdlab pro, and TMPGEnc), which as you might guess, is giving me sync issues throughout. I've converted a lot of avi's in this fashion minus the conversion of frame rate to the original avi (because of the weird 25.6 frame rate) with excellent results. I just can't understand what is going on during authoring that would change the length/duration of the ac3. A little something to confuse more... If i demux the authored files with dgindex and play the ac3 audio alone, it plays for the expected length and reaches the silent part at 1:56:28 as it should. What is going on here????

And yes ,before I'm asked, overall length of m2v and ac3 is the same.

[tinker]

I am not sure what is going on, but try MuxMan (free version), max m2v and ac3 together first to make VOB files. Import that to DVDLab, let demux and see if that help.