oop’s forgot…it happened when i tried to run particleillusion.exe version 3.0.1.1 which is 3.0.1a (29 Jan 2004), OS:windows xp home edition sp2. I overwritten the demo version of PI v3.0.1a with 301 then overwritten it with v3.0 then overwritten it again with v3.0.1a ,then boom the error appeared…