So when I scroll pages of text, there is a very disturbing shift in the text as it passes certain areas of the screen. I notice it from about the middle to the top third. It's a bit disturbing, and I'm wondering what it is and whether it's a defect that I should have looked at. My old 13" MB had no such problem. Can anyone tell me if this is a known problem, if all of them do it, or what's going on? Thanks!