Hi, I've upgraded today to 10.6.3 and everything went just fine. There's just 1 thing. My MacBook Air is now showing some weird 'shadow' on the left top of the screen. I've never seen this in my entire life. Here's a screenshot. Take a look. Can somebody please explain how this has occurred? Why haven't I seen this before when I was on 10.6.2? How can this be fixed?