Yep, typical problem with DivX converted. The prob is when the DivX is made they can vary the Freq of the audio or even frame rate to make it perfect. Unfortunately for an MPEG2 the frame rate is fixed and tre audio either 44.1 or 48.
It can be fixed though. De-mux the MPG file with TMPGEnc. Load the audio MPA file into Goldwave (or your favorite audio edditor) then you need to change the Playback Rate and then Re-Sample back to the 44.1 or 48. Save as a 16bit Stereo WAV, convert that to an MPA (I use a program called SCMPX, not sure where I got it from!) and finally remux back with the video mpv file. If all went well it will now bw in sync. If not just go back to Goldwave and change the Playback rate further and do the rest again.
Cheers.