I have HP pavilion dv7 laptop, widows 7 operating system. Couple days ago my laptop overheated and horizontal white lines (1mm in width) apeared across the whole screen, they are spaced about every 2mm. I connected the computer to an external monitor and the picture is fine. The same thing happened to me about 2 years ago, I found some instructions on the web how to fix it and the computer worked fine for 2 years. (All I remember I had to go to the start menu and change something, I think). I can't find that post anymore, So PLEASE HELP.