I have this old Hp elitebook 8440p. It was running on windows 7 and everything was fine. Recently I decided to upgrade to windows 10. Shida imetokea na graphic drivers. I cant seem to get the right drivers. I cannot change the screen resolution and brightness. Once I search the internet i get some graphic drivers by Nvidia. When i install them the screen goes off, but once i connect an external display it works just fine. What could be the problem?