Somewhere along the process of lighting my map, a strange thing happened to the reflective surfaces. They inexplicably turned purple: What you're seeing here is that the glossy checkered floor isn't reflecting the world around it, it's reflecting purple. The same with my windows. Before, they simply didn't reflect at all, that actually looked better than the purple. I know it isn't lighting, because the problem is happening in all lighting situations. Does this have something to do with my cubemaps? I placed those little cubemap deals in many places, though I never did tie any brush faces to them. The impression I got was that you just stick the cubemap entity in various parts of your map where the lighting situation has changed. I even did the "build_cubemaps" command. What's going on here?