Hey, SirBill. When my secondary monitor fullscreen problem started, I disconnected the monitor and ran the game on my laptop. It started up fine there, and then I went in and modified the graphics options and unticked the fullscreen option. That lets me play the game at least !
So, am running it on my laptop now (15" retina mbp). Looks amazing on the retina display.
Now that I switched back to windowed mode, it runs on my external monitor (but in a window only) - going to keep running just on the laptop until this is fixed, but hopefully if you try this you will be able to run the game. It's awesome!