The problem with the ones turned black is that they seem to continue to eat up memory. Those of us who are a little RAM shy need a few tricks and work-arounds sometimes. I suggest adding lights only after all figures and props are set up and posed. Save your .PZ3 with the default three-light set. That way, if you want to experiment between lots of complex light sets, you can do away with the "black lights" problem with fewer headaches. Once the "black lights" phenomenon really becomes a problem, simply re-load the scene with the default set, and start experimenting anew. By the way, the newish "Complex Global Lights" set at DAZ is outstanding ... if you switch between the diferent sets, you don't get any "black lights." If you use global light sets like this, allow yourself the optinon of adding a few strategic spots of your, pointed at the areas that need extra illumination.