An audio sync problem

I had an avi file with mp3 audio that played fine on my computer. Then, I created a wav file and encoded with MainConcept. The resulting mpg also played fine on my computer. It was then authored and burned on Taiyo Yuden media at 4x in Ulead MovieFactory. That DVD was out of sync by 5 minutes and had a severe hesitation, in the audio, every second. Same result when encoded with TMPGEnc Plus. A new wav, encode in MC, author and burn at 2.4x gave the same result. Not creating a wav and encoding with MC, authoring and burning fixed all but why, and is there any way to tell? This has happened twice before(out of several hundred burns) but those times there was no audio at all or it was totally garbled and unintelligible. Thanks