First, the answer to your big question is yes, there are different kinds of avi files. avi is just a wrapper that the particular encoder uses to wrap its file in. I would say that your DVD player only has a few codecs that it works with (that maybe an updated driver would help). I would take one of the avis that the dvd player will play and ty to find out exactly what it is. (Maybe the program Super could help) Then see if you can render that exact same format from Vegas.