I'm using Macbook Pro unibody 15". Recently, there are blue lines appear on white background on the screen but when I move the screen back and forth, those line just disappear and I could continue using my notebook just fine. The problem only happen on the notebook screen, not on external screen at all and it's often happen when I wake it up from the sleep mode. I ran Apple Hardware Test and found nothing. I already sent it to local Apple Center but they couldn't see the problem. Anyone has this kind of problem before or any idea what causing the notebook to act like this?