I have a HP laptop that will not turn off when you hit the power button. There is nothing but a blank screen and every once in a while it will flicker on the screen. I unplug it to make it go off and then when I plug it in it automatically starts up and the screen flickers for a few minutes and then blank screen. I check the hard drive in another computer ant it is all good. The DVD drive starts up and light blink. Any ideas?