I took a 720p cineform project in vegas 6, converted to mp2 and ac3 and imported to dvda 3.0. The video is smoothe on a tv set top player but jerky on a computer. What did I do wrong?

Possibly different refresh rates between your TV and your PC's monitor.

update:

The resulting video played perfectly on a set top dvd player. I tried it on another set top dvd player and some of the audio didn't play. the video portion was fine.

I've played the dvd on two computers and get a different problem: the video doesn't play smoothely, it's jittery and jumpy.