Problem: when you make a VCD, audio goes out-of-sync

This is my problem:
I usued VirtualDub to add a subtitle to a movie, but the audio goes out-of-sync with the video when the movie goes on playing (e.g. it's OK in-sync at the beginning of the movie, goes out-of-sync +0.5 sec after 1h of movie and +1 sec after 2hrs). Please note that this is the first time that happens to me with a video (I always use DivX multipass to compress the video and it never happened to me before) AND I listened to the original movie which was OK.
What have I done, probably?
What can I do to correct the movie AND to avoid to do the same thing again?

Thanks.

 

Well, since no ansers have arrived so far (I have a good time zone with respect the U.S.) I'm tying to repeat it all from the basic 'correct' movie, maybe it has been a casual occurrence.
_X_X_X_X_X_[small]Read forum rules!
http://forums.afterdawn.com/thread_view.cfm/2487[/small]

 

I found the reason!
When you open the .AVI movie with Virtualdub, the following error message appears: [bold]"Virtualdub has detected an improper VBR encoding in the source .AVI and will rewrite the it with a standard CBR values during processing for better compatibility. This may introduce up to 2.918 ms of skew from the video stream. If this is unaccepptable, decompress the *entire* audio stream to un uncompresse WAV file and recompress it with the video with a CBR encoder (bitrate: 106.7 + - 11.9 kbps)" [/bold]
_X_X_X_X_X_[small]Read forum rules!
http://forums.afterdawn.com/thread_view.cfm/2487[/small]

 

Read http://www.videohelp.com/forum/viewtopic.php?t=162340 if you have a similar problem and you are looking for some answers.