Please post the render logs that will help to track down why you are crashing at 30%.
It's odd since 2010 most render issues are with batch render not render view. If I had to make a stab in the dark, and that is all it is, I would say it's a render cache issue. You might want to bring up the performance monitor (if you are running windows) and look at the memory use as it renders.
As for threads in both batch and render view options there is a section parallelism and in that section you can uncheck automatic and try typing in the number of threads manually (In your case 16). Keep in mind, unless they have changed it, if you do not have the stand alone mental ray renderer you are limited to 8 threads. It used to say that in the output window when the mr plugin loaded but now I do not see it, but I think there is still a limit unless you purchase the stand alone MR renderer.
Also, under memory you can uncheck auto memory limit and you can type in your own value. Their is a calculate button but that sometimes produces a value that is too large and so you also crash.
Finally, if you have mental-ray satellite running make sure it's configured properly or turn off render to network machines.
Best of luck,
-rick
"If I have seen further it is by standing on the shoulders of giants." Sir Isaac Newton, 1675
Last edited by ctbram; 14-09-2012 at 01:36 AM.