It seems that rebooting the Surface Pro 3 with the TypeCover folded back causes it to freeze at the boot screen. I've tried this on some of the models in an MS Store and the same problem persists. It eventually booted back to the desktop after about 5 minutes. I have found a few threads regarding this issue and I think it has something to do with the November firmware update. Hopefully, Microsoft is aware of this issue and releases another firmware update in the near future.