Actually, this sounds more like a feature of WinDoze than of Poser4. I've had other programmes than Poser refuse to start because of "missing .dll" blues. What might be a good idea is, once you've followed beelzebulb's advice about re-installing - is save a known working copy of the dll in a zip file in the directory in case this happens again. Sometimes this works, sometimes it doesn't, and sometimes there no other option that to re-install WinDoze Paul