I've got a video in Vegas 5 that has 43 markers throughout. I'm rendering it to an .avi file with the markers in place so I can use them as chapter markers in DVDA2

When the media is imported into my DVDA project, all the chapter markers are offset by about 30 seconds.

I'm not about to go through the whole video to realign the markers; so can anyone explain why this might be happening?