Thanks for your advice. I did look through the NVIDIA documentation, but somehow missed that bit on uninstalling it. Thanks for everyone's help.

Oh well, no help here. One thing I need no advice on is to uninstall OctaneRender.

Thanks, I thought that might be the problem.

One question: how do I uninstall CUDA Toolkit 4.1?

Thanks!

OctaneRender® Beta 2.57 doesn't want to start on a 2010 Mac Pro.

I tried launching it from both 32 and 64-bit kernel starts. Crashes every time.

Mac Pro has:
two NVIDIA cards, Quadro 4000, GT 120
CUDA Driver 4.2.7
CUDA ToolKit 4.1

Mac OS X 10.6.8
24 GB RAM

The splash screen appears then ...