I'm getting the same error. The movie is Bagger Vance. What gives?
I think I may have figured out the problem. As I have witnessed in the past, DVD2one does not like being fed any files that are not straight out of Decrypter. If you have run DVDshrink or any other program on your files, DVD2one seems to always choke on it. Not sure why. In this example, I had run DVDShrink on the movie and reduced all the extras and supposedly left the main movie alone. I separated the main movie and created IFO's and tried to run DVD2one on it-it failed. I took the original main movie and separated it in the same way, and DVD2one accepted it. Draw your own conclusions.