My ti-book's screen (550) will go almost dark at random times. I have set the energy saver to sleep never...2 or 3 hours, nothing makes a difference. I can see faint shadows of the screen images and my keystrokes are being recorded, so the computer has not crashed. The only way I can get the screen back is to close the cover and reopen. This can happen every couple of seconds..or after a long time, it's totally random. Does anyone have an idea what the problem might be?