Try running the system in OpenGL mode and see if that works.
Close all files and then switch it on under Tools > Options > Performance
I think that I got it figured out, although I don't know exactly what was causing the issue. I re-structured the Feature tree and it has been working fine. It was like the software was caught in some loop as soon as I selected sketch. I was watching the cpu cycles for SW in task manager and you could see that it was doing something. It just would't quit.