Please guys and girls help me with my laptop!?

I was playing Quake 3 Arena and suddenly my laptop shut down.Quake 3 Arena is not installed,just click and play.Whenever i switch on my laptop in my account alone the desktop appears ver very bright and i can hardly see a thing.But when i start Quake 3 Arena and then quit it then it beccomes normal.Please help!I have Toshiba A300-15c