2011 Macbook Pro: Purple Screen of Doom?!

Recently, when I've been using a web browser (and I've experienced the problem when using Google Chrome AND Firefox), my 2011 Macbook Pro 15'' freezes sporadically and the screen turns purple with some pixelated greyish splotches. After a moment, it stops, but there are some spots left behind.

For instance, I was using Chrome, it froze up on me, and I attempted to quite and force quit. Suddenly, the whole screen did the weird purple thing, and when the screen cleared, I had had stickies open and in the places where the stickies were, the purple and grey remained.

I feel the need to mention that my laptop has been getting VERY hot lately (so hot, one time, that the fan turned on in a fan-of-doom manner, as it was loud and scary!). I'm not sure if this is effecting the problem, causing it, or what. I had the same heating issue with my 2006 Black Macbook, but it worked fine otherwise besides having to replace the hard drive twice over it's lifetime (I eventually reformatted it and gave it to my mother, who mainly uses it for Facebook and playing Jenga online so I don't foresee her light usage causing it any conniptions in the near future, haha).

Any help?! Advice?! Solutions?!