I have an odd bug when trying to load the game - as soon as I click 'play' and the option shows to play either Beyond Earth or the 'AMD Mantle' (whatever that may be). I select the first option, the box disappears, and nothing happens. Then, a few seconds later, the option box reappears again. Has anyone else experienced this, and if so what's the solution? I just upgraded my PC to Windows 8.1, but have verified that other Steam games still load correctly.