Fellow Moviefactory users, help needed please!

[Yucko the Clown]

I've relatively new to using Ulead Moviefactory. I've authored a couple of dvd from avi's so far. At the beginning they look great and everythings fine. Then about 40 minutes or so in the audio goes completely off from the video. This just happen out of the blue. Its happened on both dvds I've done so far. Can someone please help me out here? I can't be the only one this has happened to. Its so strange cause everything looks fine then boom. Any help would be greatly appreciated

[flt123]

how are you autherising the avi??