We've had quite a few folks report the same symptoms as you. It happens on MacBooks also. It usually turns out to be a case of cable pinch. There are numerous cables that snake their way from the logic board up through the hinge area and finally to the display.

What may be happening is that one of the cables is being pinched or pulled too tight when the lid is moved in a certain way. That can temporarily dislodge (slightly) a cable from its connector causing the weird symptoms you described.

Go to iFixit: The free repair manual with your model number on hand and look up the take apart instructions. You may be able to fix the problem yourself if the machine is no longer under warranty.