I was playing Civ 5 online with my friends online when suddenly my monitor turned black. It turned out that my computer had turned off and the monitor then displayed the motherboard startup menu. I am then taken to a screen which gives me the options to start windows normally or launch start up repair. When either of these options is selected it briefly shows the screen you should be taken to before going black and returning to the motherboard startup menu. This continues in an endless loop. Can anyone help?