I think your problem is in the "DivX" world - perhaps Xvid, or some other popular AVI encoding format. Actually, it's not with the DivX or Xvid itself, but likely with the audio codec used to encode the film originally.
Grab a copy of the free "VirtualDub" - a google will yield the download location. This software is able to re-encode the audio track while not touching the video portion, making it align (if you use the "Interleave" menu) over time. It may eve warn you about odd audio offsets when you load the errant Divx movies. Re-encoding the audio by itself is much faster than audio/video encoding (xp1800's can reach 150-250 frames per second).
Try various audio options - consider looking for the Lame MP3 codec (if you don't already have it). The "new" Divx file may have fewer problems in your attempt to create a DVD.