I have an Inspiron 1501, recently the screen began to flicker and go black. It has now become black and won't recover. By black I mean it appears black, however you can still see it with a flashlight held close. I ran the diagnostics and received one code: 2000-0333 "graphics test timed out waiting for keyboard response". I am using an external monitor and it works fine that way. Any idea what the problem might be?