I have an old P4 based PC, currently running Windows 7 Pro, which has just started booting incorrectly intermittently in a strange way, jpeg attached. Half the screen is black and the system just hangs and there is a low hum beat which comes and goes through the speakers. If you turn PC off, leave for a few minutes and try again every thing is fine. Next time I boot the black area on the screen has increased in size, at the moment about half the screen, and everything hangs again. I just wonder if you think this is just the signs of an ageing PC or could it be a specific problem or component that is about to fail and could be rectified.