Curious Labs offers a "Memory Upgrade" that solved my problems. Apparently Poser 4 (and PPP) couldn't handle installed memory larger than 512, which causes a problem with larger files that require more memory in order to load and render properly. Don't know if this will be an issue with P5 or not.

Intel Core I7 3090K 4.5 GhZ (overclocked) 12-meg cache CPU, 32 Gig DDR3 memory, GeoForce GTX680 2gig 256 Bit PCI Express 3.0 graphic card, 3 Western Difgital 7200 rpm 1 Tb SATA Hard Drives