please help - strange black lines constantly on screen

[macusermlk]

recently i've been having problems on my mac as its begun to slow down drastically over the last few days and i've been seeing these strange outlines around some of my programs (see image). any assistance/advice would be greatly appreciated. thanks in advance.

 

[Queso]

What model is it? Some of the 2007 and 2008 MacBook Pros had a dodgy graphics chip, which could cause those sort of blocks and missing screen pieces. Nvidia GT8600M if memory serves.

Go into your Apple menu (top left hand corner of the screen) and select the About this Mac. option. In there is a button marked More Info. Click on that to see what graphics hardware is installed.