vob audio sync prob

[Mr_Dell_Boy]

i conveted a avi to mpeg(using tmpgenc and v-dub) and then to dvd vob files(using ulead) at all stages the film is in sync with the audio except for the final conversion to vob, it starts in sync but loses it the further it plays, we tried we some diff films i found that sometimes it is stretching and other times it's compressing the audio. is there any (easy) way to correct this during conversion to vob or after.