Nobody can tell you anything without proper system info or other technical details like what your MP settings actually currently are.
Well, now i know.
Mac pro 2012 2x2.4 GHz 6-Core Intel Xeon
48 GB ram
AMD Radeon HD 7950 3072 MB
startup disk - owc 960 gig ssd
cache - 480 gig ssd
osx yosemite 10.10.2
AE CC2014 up to date.
For more than 90% of my projects mult processor rendering is not compatible with anything. Just turn it off. It's buggy and most of the time not worth it.
If you DO want to use multiprocessing (which I do much the time), send us a screenshot of your memory and multiprocessing settings.
What sort of error messages are you getting when it crashes? Can you share the crash logs? Explain in as much detail as possible what your composition looks like (plugins, codecs used, etc.)
no error messages. just stops rendering, cpu drops for 90% down to 2%.
usually i then force quit. after effects then tries to open, but just sits with the little blu dot over the app icon and never opens.
i try to restart, but nothing happens,so have to hard restart.
happens with a comp with 2 layers, happens with a comp with 200 layers, doesn't seem to matter.
im normally left with standard render.....and a very long lunch.
For more than 90% of my renders I use the Adobe Media encoder and keep working in AE while the render is happening. I can't afford the time to sit around and wait for things to render. I haven't since the AME was introduced. Before the AME I used a 3rd party solution for rendering in the background.