the core and renderer of poser 5, 6, 7 and PP are not really changed. theyve added new features, tweaks, etc but if you are putting together scenes that make Poser 5 hang indefinitely then do not assume that an upgrade to Poser 7 will necessarily render them smoothly.

IMO have a look at your lighting, shadow and render settings/options.
try a simple troubleshooting process of rendering at low settings with no shadows and 1x AntiAliasing in workspace resolution first, if that renders then try with higher settings, etc. it might just be one simple setting causing it to hang like texture filtering, etc.