One comment I would add. It's just a gut feeling I have, rather than anything tested... but I don't think it's custom names per se which causes the problem - in fact it's the opposite in this instance. Renaming the lights serves to turn off LGHT1, LIGHT2 and LIGHT3 (which were already in Poser's memory) rather than replacing them with a new set. Ronstuff.. this may also explain why on some occaions your lights went against the grain an masse. I find it a very interesting discovery that simply renaming the lights eliminates the problem. The possibility of a conflict with the lights Poser has in memory and some subsequently loaded sets remains. It appears even more likely in view of such evidence.