I have a PowerBook G4 (Ti) 1GHz and recently I've been noticing some problems with my screen. Every now and then, the blues in the screen will start to flicker or discolor or lighten. Since my desktop is pretty much all blue, it causes these lines to race up the desktop (hard to see them unless you look closely.) When I look at photos, all the blue's look discolored and too light. When I hit any of the Expose buttons, the whole screen starts to flicker. I'm sure this is a hardware problem because when I physically smack the side of the computer, it seems to go back to normal for a couple seconds. I had my screen replaced back in November because of white splotches on the screen, and I'm wondering if it was just improperly installed. Anyway, I'm wondering if anyone can give me some insight in this. I have AppleCare on my computer so I could just bring it in I guess, although because I can't consistently replicate the screen problem, I feel stupid bringing it in and having some "genius" look at me like, "dude, there's nothing wrong with it." Any help would be great. Thanks.