The "render to image files" solution is the best one I know of if you don't have Poser 5 SR4.1 (which as you've got Poser 4, you won't have).

If you render out to a sequence of image files then you can use the "Animation Palette" to select the range to preview and render. If you crash at frame 150 then set this to go from 151 to end when you reload, and rendering will resume at frame 151 :)

As a matter of interest, if you render to image files this way then you can fairly easily adjust small parts of your animation and only re-render the frames which have changed :)

Cheers,

Cliff