DVD burning and sound lag

Hi all... I recently downloaded a movie file from the internet and after
burning it to DVD I find that the sound lags behind the video. This
effect can hardly be noticed at first but as the movie plays on it
becomes more pronounced. The files where of the type .vob, .ifo and .bup
and I used Nero 6 burning rom to do the burning. Has anyone encountered
this problem before? Is the problem on my end or is it the case of a bad
rip somewhere along the line?

Thanks
Newfdog

Newfdog