Blue, Green, and Yellow Pixilation (Pic Inside)

Hey guys, how you doing?

Quick concern, hopefully someone can help me out or give me an explanation as to why is.

I am running a 2.16 GHz Intel Core 2 Duo iMac (Version 10.5.5)



I get these pixelated boxes apperaing here and there, but as soon as I click and drag over them they dissapear, or if I move a window over them they dissapear as well....and body have a answer or solution to fix this? Thank you very much for your time.

Looks like a graphics card issue

Does it happen all the time, and does it happen in any other user accounts

latley it has been happening a lot - especially when I run pro tools