I have both Windows 2000 and 98 on the same machine, 98 does that all the time in Poser, especially when you are rendering something that you have made a bunch of changes to and you haven't yet saved! ;-) Win 2000 doesn't do that, I have 768 Mb of RAM, incidently. I'd gather XP would work just as well, but I'd rather have 2000, myself. Less junk to turn off, if nothing else. XP is the operating system of the moment, of course. If you have seperate disk partitions a dual boot system is nice too, so you have something to fall back on, you can get utilities to partition your current drive on the fly and then just add 2000 (or (I think) XP) retaining your old as a backup. You than get a little menu on startup asking which one you want to boot from. You can even run the same installation of Poser on both - I do that. Eventually Microsoft would like us to replace our operating system yearly, as they could use the money. Curse you, Bill Gates!