Hi! My MacBook Pro won't load whenever I try to turn it on. When I press the power button, I hear the greeting chimes, and the white screen with the apple appears. Either the loading circle or the bar (or both) pops up for a moment under the apple and this lasts for about a minute, then the screen goes black. Nothing happens if I press the mouse or keyboard keys. I've turned it back on about three times and it keeps doing the same thing. And it is fully charged.