@CBrown Can you force quit SketchUp using Task Manager?
Sometime SketchUp will go into a 'thought loop' when you ask it to generate wild amount of geometry.
I can't see what it is you asked SketchUp to do other than 100mm wide bevel with 6 segments per bevel. You could just be hitting the upper limit of geometry generation?
Try forcing SketchUp to close. When you restart SketchUp use File > Open to open the file again and if there's an .skb file it will open that and ask you to save.