I have a Core Duo 1.83 GHz MacBook Pro. I've tried all the obvious things like repairing disk permissions, restarting etc..., but it still stutters. I downloaded the Halo Wars HiDef movie to play in QT utilising Flip 4 Mac (it's a WMV), and it stutters (very badly) when playing the movie. It goes down to about a frame every 4 seconds. When I open Activity monitor, it says the process is using 100% CPU, but the stats at the bottom say only 50% is being used. Is this because Flip 4 Mac isn't designed to use both CPU Cores? It seems unbelievably sluggish recently, randomly freezes up for any time between 20 seconds and 10 minutes, plus feels incredibly warm (I'm used to it feeling very warm, I've had it for about 6 months now, but this is abnormal). CoreDuoTemp and smcFanControl both report around 62-65º constantly, up to 90º when listening to iTunes + web browsing. I've had other weird issues like the screen fading out at the left too. All in all, it's a pretty unhappy MacBook Pro. Only thing that doesn't seem wrong with it is I haven't had a Kernel Panic in about 2/3 months, although it does occasionally freeze up completely without the message... I have 12 gb of free HDD space (on an 80 gb drive), and I've already re-installed OS X a few months ago. I'm on 10.4.8 too, all up to date. The problem is that if I take it to Apple, they'll do what they've done before which is to stick it on their advanced diagnostics which takes a few days to run, and then if there is a problem, it will take ages to get a new one because it's non-stock (Core Duo, not C2D). I'm using it for coursework etc... in school at the moment, so I can't really be without it. What do you guys, in your infinite wisdom suggest?