The program you are using is Sonic MyDVD I suppose. What version btw?
My first guess may have to do with your Hard Disk Drive. How much space left is your HDD? Does it have enough sufficient space to store MPEG-2 video before it burning.
As you can see, the AVI file will be converted to MPEG-2 by Sonic MyDVD, and after it finishes encoding. It will burned them into the disc, including title, menu and all...
I have experienced before where the disc doesn\'t burned all the way and also have encountered where the encoding just stop partway.
My guess for this have to do with hard disk drive. Just make sure there is enough space and also remember to Disk Fragmented your hard disk drive.