Hi Richard,
The MAC is a 2.66Ghz MAC Pro Running 10.4.8.
The peferences are set up correctly as per your screen shot.
In the catalyst control it reports 4 video channels.
In the HUd, inputs section there are 4 boxes and they show that all video inputs are off. If I tick the box it appears to try to load some settings and then returns back to off. I have tried versions 111 and 097.
Thanks
Ian