Hi Richard, I'm glad that solved your problem!

Right now there is a bug where if you get one individual surface with too dense of a display mesh on it, MoI will crash to desktop like that. That's why a half-circle one worked, because it was smaller it had less polygons in the display mesh and didn't go over the limit.

I've made a slight tune up for the next beta to make it less likely to run into this limit, and I'll do a more proper fix for it in the next beta after that.

- Michael