Rendering Bugs?

[Vitruvius]

I've been having problems with AC rendering. In the attached image, the cone object shows no checkerboard pattern in OpenGL, and no ground shadow when rendered in Lightworks.

I've run the same test on an iMac G5, iMac G4 and iBook G3 with identical results!! The model is OK as it's Dwights model opened direct from the PLA file with no alterations.

Is this an Archicad problem? Or OSX? Has anyone else experienced it?

[Vitruvius]

And some similar weirdness in LW - Lightworks for ArchiCAD ambient light exercise (Page 40).

Set up per instructions, my rendering with ambient light (intensity 100) yields a black hole. If I boost the ambient to 600 I get an image approximating the manuals image (page 40, upper left).

Any suggestions as to what gives? Is this due to difference in display cards?

Setup:
iMac G5 (1.8 GHz / 1 GB sram)
OSX 10.4.3
ArchiCAD 9.0 + Hotfix 4