After trying a dynamic cloth simulation twelve times with various adjustments (collision depth, collision offset, etc) in P8, I now rather suspect that the dynamic cloth simulation feature itself is screwed up in P8 & PP2010. 

The scene simply dropped a blanket onto a sleeping dollie.  In P8 the simulation initially seemed to be running well, but then it went divergent and formed bizarre distortions of the cloth.  It also seemed to partially ignore collisions, with parts of the blanket dropping through the doll, the mattress, and the floor.

I opened the same scene in P7 and ran the simulation -with the same settings- successfully.  When it finished, I went to the last frame and exported the blanket as an obj.  I then imported this obj back into P7 and saved it as a prop.  I was then able to use the blanket in a PP2010 render.

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