I probably don't know enough about this to even speak to it, but I know Poser 5 has some problems with the lights. I have XP Pro and P5 still freezes up consistently on some light sets and not others. As it happens I get rid of the lights that cause the problem. I don't have the DAZ lights, but do have EII lights. They work fine no matter what :) So do P5's default lights. My guess: P5 is the culprit...not the DAZ product or your 'puter :)