Crash: converting planar curves to a surface

I just started using Rhino for Mac. The app crashed twice when trying to convert planar curves to a surface. The app froze while working with control points. Closing and reopening the app solve this problem which was intermittent.

Hi George- so far, OK here - if you think this is related to any particular curve or curves, please post the curves here, or send to with instructions as to how to repeat the problem.