Too hot on the lights.. (too many). IDL can do this with one light. Even set to 80% or less. I'd turn off all your lights save one "sun" or 2 for "2 suns" if that's the case. Perhaps a second spot set to specular only for surface quality. The rest,, just try it out in the material room. Takes a few seconds. Try a HDR image. Tons free on the net.