Hi Robert,
I managed to get 30 minutes on the 'difficult' machine with the AMD ATI graphics on it. I did finally find a tick box that gave me the graphics... It was the 'Use 256 colours' that's available in the compatibility tab (right click on the mathcad icon and select properties).
Obviously the main (background theme) display is totally messed up (It had been a nice picture of London bridge and it went all 'funny ;-)
However, it did display the 3d graphs almost properly (the odd black bar at the bottom of regions when scrolling), and recovered when clicking into the 3d region.
Hopefully I'll be able try try our full analysis 'app' which uses an animation and captures 3d & 2d and numeric results for replay, and we can compare results from the different PCs.