Today I bought Assassin's Creed II from the Apple App Store and installed it on my Macbook Pro. Upon being opened, the game briefly runs normally by displaying the Ubisoft logo and then the AC2 title screen. However, once I click the title screen, it shows the selection menu (Story Mode, Options, Exit to Desktop) for only a moment before the entire screen goes black. The computer has not been shut down, it simply seems to be frozen on a black screen, accompanied by a rhythmic low beeping sound. There is no way to exit the program and I am forced to shut off my computer.

Can anyone help?