I have Win2K SP2 and IE 5.5 SP1 (Use Netscape 7.0 instead) and I have experienced one problem so far with Poser 5 (other than the inherited Poser 4 bugs that stll need to be fixed).

It was during a 144 frame Production mode FireFly render. Poser just kept on eating up Virtual Memory on the disk until it took most of it and brought down my system. I think it might be a bug, but I'm going to render a smaller animation and monitor everything.