Graphics Error after using Instant Alpha

I was using Instant Alpha in Keynote on a picture obtained through the media browser (which gets photos from iPhoto). I was dragging the instant alpha thingey when all of a sudden, my apps and the dock suddenly became this fuzzy squares pattern of purple and whatnots.

Any idea why this happened? I had Keynote and Adium running at the time, that was it. I wasn't even chatting in Adium.

The annoying thing is that my macbook pro is not even a week old, and this happened. My mac hung twice before as well, within this one week alone. I haven't even done anything considerably intensive (I'm just a simple uni student) and I am worried that there could be a deeper underlying problem to this.