How much of a problem is this? (Graphics)

So i've had a macbook pro since last november and soon after i got it Starcraft 2 came out. So i got it and played the game on "medium" game settings, which is what is recommended. Until about december it worked fine but then it started to do what happens in the picture when i played the game. So i put the graphics settings down. But then it happened at random times on the "low" setting. I thought it was just SC2 but i was then playing Modern Warfare 1 and it happened again. The only way i can fix it is by restarting my computer.

Sorry it kind of hard to notice whats happening in the pic but the pixels just fly all over the place and crazy stuff happens. It starts in the game but then continues anywhere.

Thanks guys

View attachment help please.pdf

Has anyone had this happen to them also?

P.S. the pdf attachment is a pic of my desktop showing the problem i have.

And it doesn't open - Preview claims it's a damaged file.

How about posting a screen shot instead?

Well i did take a screenshot using Grab. But it saved as a tiff file and you guys dont support them. So i have a tiff file of it, how would i post a screenshot without using Grab?

Use Xee to load the TIFF and then Save As to JPG which is supported by the forums..

Regards