Movie out of sync midway through playback

I am burning AVI files onto a DVD using DVD flick used Nero but the movie’s audio totally out of sync. What I am finding is that, with DVD flick, the audio/video sync is good then part way through the show it pauses, then continue but the audio is about 1-2 sec out of sync. Any suggetsions how to fix this? The movies play all right on my computer.