I was in the middle of fighting the Butcher, the game then froze. Sent me back to my character loading screen. I logged out to see if that might fix the problem. The game then froze and had to force restart my Macbook Pro. When I tried to reboot the game after my computer had restarted, it says please install the game.
When you click install as it asks, the error messages explains "data required to install this game could not be found. Please try again. If this error reoccurs, please try installing Diablo III as a digital download on Battle.Net