After running for a little while, my laptop screen goes bright white static pattern. If it happens while connected to tv by hdmi, the display remains visible on the tv just fine. If I unplug the hdmi, the screen display restores. It also goes white static when not connected to the tv but in that case, if I connect it via hdmi, the screen display restores. What is going on? I have replaced my hard drive and reloaded Windows (7) and it still happens.