John,
I have this happen a lot. Look where the drawing stops rendering, it is probably at a pull or a rope molding or something else that is causing an overload. I get around it sometimes by saving the job then completely shutting down the computer (not just a re-start) then upon starting the computer up again go immediately to your render and try it while the computer still has a lot of resources. If it still hangs at that spot, remove the pull or molding that is causing it.
Kerry