HELP! have black grey blocks on screen..

i have black and grey blocks that show up on my screen. they vary in size and come and go. also the icons on my docks and some of my windows like ichat are bordered with black lines. if anyone can tell me how to fix it please help me thanks.

here is also a picture. black blocks on top left of this screen shot but they always very in size. also i just downloading shiftit and starcraft 2 beta maybe that might mean something.

Welcome to the forum. What does the desktop look like without the game loaded.
What Mac do have and what OS is on it?

i have mac os 10.6.3 2.2Ghz intel core 2 duo 4 gb ram. well the game isnt running that screen shot. but those black lines shouldnt be around my dock icons like that. thanks for the welcome

Try doing a Hardware test to see if that shows up anything - it came on the install discs that came with the MB

i did the hardware test and it showed no problems. and the blocks are still there!?!?! is there anything else i could do