I have a sept '08 white macbook. I was having trouble with the trackpad being kind of jumpy/jittery in response to my touch (plus the keyboard was not recognizing the first key-press or two), which the apple genius bar guy confirmed was problematic. So, my whole top piece (keyboard/trackpad) was replaced. Fast forward a couple of weeks... i'm noticing that while the new trackpad has much better response then the defective one, but there's some kind of new problem (maybe it was there before, and I didn't notice it, but anyway)... HERE'S THE PROBLEM: I will be using any particular application (adium, skim, preview, whatever) and everything is fine. But then, randomly, when i'll go to click on some other aspect of the open window/program that I am working in, the macbook does not want to respond to my clicks by the button or the trackpad. I wiggle the pointer around, click on something else on that same open window/application, no response again. I click on another open app and it will always respond+come to the front of the screen. I go back to the other window/app and it responds just fine again. What is really weird is that this same problem is occurring even when I use my external USB wireless mouse. It's like a software issue or something. I want to see if 10.5.6 fixes this... but does anyone even understand what I'm talking about? EDIT: This problem also LOVES to occur when i click an icon on the dock. Usually i'll have a program running and it will be minimized on the right side of the dock, and then i'll click the program's main icon and there will be no response at all. I go click randomly on some other window and then come back to the dock and click on the same icon again, voila! It works again. Frustrating.