using 64-bit CPUs with a 64-bit OS?  - Yes

bad RAM? - NEw PC, checked at build, RAM is ok

bad graphics card/VRAM? - Brand new card with all the latest drivers, checked on build, no other apps crashing.

too many figures/textures in scene? - one figure in scene.  If one is too many we're in trouble.

bad display prefs/scratch disk prefs? no idea what these are, please explain.

remove unused masters? - yes, makes no difference

what is frame size in pixels? no idea where to find this

after how many frames does it run out of RAM? - sometimes around 10, sometimes around 70

can poser finish the same animation? - Poser can not only finish the same animation, but even some where three of the same size are added one after the other, the same model (Hiro) with more clothing, and other objects added in the scene.  No doubt Carrara is much faster, but Poser doesn't crash.