So my friend has an older Asus k53t laptop, and I can not for the life of me figure out what the problem with it is. When it boots up, it works for a few minutes max, then the screen goes black and it becomes unresponsive. It's not an OS problem, because it does it even in the BIOS. I don't think it's a display problem, because the backlight stays on, and when I hook it up to an external monitor through its VGA out port, the external monitor shows a black screen as well. Any idea on what the problem might be?