It's a bit of a problem that the progess bar doesn't seem to do anything at some stages, such as Loading Textures -- it's hard to tell if things have hung at that point. That's why I suggested trying an overnight run. If that works, it's likely a shortage of physical RAM. I've suspicion that ray-traced shadows may sometimes be faster than shadowmaps. Probably depending on lighting, for one thing, and scene complexity. You don't have to generate the shadowmaps, and then you start seeing the picture sooner. It might even be just that you see something is being rendered.