sounds like they maybe some sort of global lighting.in global light sets the lights that look black are not actually black.they can be any color but they look black because the intensity is turned down very low.most global sets have more than 20 lights which takes up ram.poser is a real ram hog and the more objects you have in a scene,including lights,the more ram is taken up.it also sounds like maybe you're importing the lights as pz3 files.this has never worked for me.any time i import a pz3 the lights come out all screwed up and have to be deleted.the only way i've been able to get a pz3 light set to work is to close poser and double click on the file.this will open poser with the light set working properly.it can then be saved in the library.the down side to this is it always screws up the way i have the interface set up.i always have to reset everything and resave to prefered state.also some light sets point to a character.if there are only props and no characters in your scene the lights may not work properly.another thing that can screw things up is if you don't have all the current patches for the version of poser you're running.4,pp and 5 all have bugs and need patches to work properly.