I've originally posted this on Apple Support Community, but maybe the people of MR have a faster and better answer. The previous post described the issue: And my answer: Walker131, I'm having the very same issue. My configuration is: Late 2009 White Macbook Unibody 2,26GHz 9400M (MacBook6,1), OSX 10.6.8 Looks like it happens only when using Google Chrome. It can be caused by a graphics hack that only Chrome employs. It acts just as you described - a quick blink apperantly inside the browser's document area (DOM container). When it blinks, I can see the desktop image behind or a window from a background application. It's a fast 1-time flickering which looks like a subliminal message and occurs frequently when using Google web apps (Gmail, Google Search, etc). I was concerned if this could be a failure caused by a cold bga soldering in the graphics adapter, but I presume it's not the case after reading this topic.