I had problems with V4 from day one, had them till V4.03, updated to 4.05 and seem to be running an extremely stable V4 at the moment, since 4.03 I can even import Poserthingies but who needs that with the new radiosity scripts. The last crash I had was before 4.03 and I usually push every button in sight. What I don't try to do is run the thing in openGL mode, because the Nvidia cards aren't too good at that and I've no need for shady previews.