I run it on a dual processor system under XP and it has froze and forced a few Ctrl-Alt-Del-End Tasks after going in and out of the face and hair editor to many times. (Whats the best Image size to use from a digital camera?) It is also running way slower then normal. Render times are great with firefly and shadows active witch seem kind of odd but trying to move things around and making adjustments and scaling are very difficult. I cant say that I have had this much trouble with Pro Pak.