Quote - Hi Erik.

The simplest thing is to change the material to Matte and set the Diffuse color to White.

See if that works before doing something drastic.

Cheers.

Squeezed a render in just before dinner, made all offending parts matte white, and they render fine (in white). So I'd say there's nothing wrong with the geometry itself.

But what is it then?

Could it be my graphics adapter is broken or overheating?

Does LuxRender use it in a different way for metallic surfaces compared to glossy and/or matte surfaces?

Erik