It isn't a lack of RAM.  1Gb will not be overwhelmed by loading one doll and accessories.  Something else is wrong.

Quote - Do you have all Service Releases installed?

  This is important, according to what I've read about P5, as it had serious bugs in its initial release.

Does anyone know where service release updates for P5 can be downloaded?

Poser 12, in feet.  

OSes:  Win7Prox64, Win7Ultx64

Silo Pro 2.5.6 64bit, Vue Infinite 2014.7, Genetica 4.0 Studio, UV Mapper Pro, UV Layout Pro, PhotoImpact X3, GIF Animator 5