I've done so several times. The only time you have to reinstall is if you move that drive to another computer. You do need that CL memory fix I quoted though or system gets confused and you are stuck with rendering in the display window. Whether you defrag or not. My worst probs came right after a defrag and cleanup of temp files. Haven't done it with Poser5. Now that the security's off it should be possible. But I don't know for sure. Emily