hey, this problem started about a month ago. First of all, I have a gateway fx p-173x notebook. basically my problem is randomly, usually when I'm playing a game, i will start getting some moving black lines along any white shown on the screen. Sometimes these lines move faster and sometimes slower. In addition, this only happens on a white background. Then this problem will occur usually anywhere from 5-10min then will go away. I have tried turning off my laptop when it happens but it still appears when rebooted, it just goes away with time then another day will randomly restart for 10min.
So i was wondering what could be causing this? Is it a overheating graphics card?

I have used a compressed air can too clean out the airvents.

laptop specs: 3gb of ram, intel core 2 duo t7500 2.2, windows vista ultimate
8800m nvidia geforce gts