Right, caulbox, but I'm still not convinced that it is JUST a naming problem - I think that sometimes renaming the lights actually prevents the problem and other times may contribute to it, but it is not the names themselves that cause the problem. I think in renaming a light we force poser to update the entire light parameter list which automatically fixes any potential problem that might be lurking until render time. In other words, the real problem is in the update process done by Poser when a light set is switched. Something is not translating properly here from one light set to the next when they have several common lights with different parameters. Here is an interesting test which I can get Poser 5 to freeze 100% of the time - see if you or Emily can try this: 1) Launch Poser 5 to the factory state with the default lights and Don in his whites. 2) Switch lights to the DNA Creed Lights 01 - (first one on the list "Bark at the moon) and render the scene. 3) Switch lights to the DNA Pastels (first one on the list - Pastel 001) - and try a render. On my system, it freezes 100% of the time even after a fresh reboot. The funny thing is that on the surface it looks like both DNA light sets use Light 1, Light 2, Light 3 etc for their names. The difference between them is that the DNA creed light has no Lights 2 or 3, but it has a Light 1, Light 4 and Light 5. The Pastel set uses Lights 1 thru 4 but has no Light 5. Also the lights in one set (with the same names in the other) must change from inf to spot or vice versa, and maybe this is what is causing the problem. Anyway, I'm still tracking it down.