My pc switches on but doesn't boot. I normally just get a black screen with a flashing underscore in top left corner. I can get into the start up menu and then the boot menu and boot the pc that way. I have on the odd occasion received an error message, something about the keyboard, i cant remember exactly its been a while since i seen that message. I know nothing about taking a pc apart and testing hardware, so im hoping its a software issue. Any ideas?