Shanna, as a happy Mac Poser user, let me say welcome. What you're trying to do is install a Classic (OS 9) application onto a machine which doesn't have Classic installed. Poser 4 will not run under OS X. Poser 5 will. So you have two choices: get OS 9 properly set up, or purchase Poser 5. Whoever installed OS X on the G3 didn't leave you with an OS 9 volume-- which is strange; OS X does not run particularly well on the G3 machines. It is not a trivial thing to create an OS 9 volume -- if that's the way you want to go, then you should find someone who's competent with Macs and have them take a look at it. If you're near a city with an Apple store, they will set up software for you. . .this is what I'd suggest, because its too hard to tell from here what your current configuration is. . .