My engine uses GLSL for all high-level shader effects. I've tested the engine on two ATI GPUs and two onboard Intel GPUs, and the engine runs perfectly. It was tested on various nVidia cards today, and all of them produced "polygon soup" rendering. I disabled the engines GLSL, and this issue went away.
What's causing this on the nVidia cards? What are the differences in the way ATI and nVidia cards handle GLSL?
I didn't test on my computer, so i'm not completly sure of the system specs, but they are somthing like:
2.17 GHz processor
nVidia GeForce 52xx FX (possibly higher)
512 MB RAM