I'm having the same problem with my 3 year old MBP. Which I bought October 2007.
Weird "squeezing" of square blocks of the screen, as if a rectangle were squished into a triangle by moving one of it's corners up to touch the other corner! But only in a small (seemingly random) part of the screen.
Black vertical bands appearing in a window. Random color bands appearing.
Screen went BLACK once, and refused to respond.
Another time, I got a spinning ball of death. The entire screen went bezerk, wierd colored patterns all over the entire screen, that gradually got more intense. I would have looked at those colored patterns for longer if I didn't get the feeling my Mac was cooking itself to death.
Another time... I got another error, but I can't remember what it is right now, but it did require me to restart the Mac.
Not happy. it's only 3 years old. I got a 5 years old G5 iMac sitting happily downstairs, works perfectly, and probably has 5 more years of life left in it.
I've heard, but don't know for sure, someone said its because the solder is overheating. Should I really have to get a new computer just for that??
Apple seem to be running Macs too hot. I turned up the fans to 4000, using FanControl, it still sounds quiet? I'll try using CoolBook although its a bit daunting. I'll try using the thermal paste.
I'll ask Apple about this, but I don't have my hopes high.