GRAINBELT Why are you spending the additional time having VH create a disc image? If you're converting AVI to DVD, all you need is the VIDEO_TS folder, which can be played by DVD Player or VLC, and can be burned directly to DVD in Toast by burning the VIDEO_TS folder in either Data mode or Video mode (select the Video_TS option).
VH is a wicked app... seems like the problem you're having is specific to your Mac, and also unnecessarily encountered anyway.
(Version 1.21)