Same problem here!
2010 MBP with 8GB aftermarket RAM, NVIDIA GeForce GT 330m 512mb, 2.66 GHz Intel Core i7, running OSX 10.9.2. Yesterday I was running Wineskin, Outlook, Excel, Safari, Firefox, Skype, and iPhoto when all the sudden the screen froze, then became covered with multi-colored pixelated bars running in a herringbone sort of pattern across the screen. Tapping the housing changes the color/layout of the effect, sometimes its static and other times flashing like crazy. As soon as this happens, the entire machine becomes unresponsive - the cursor disappears occasionally and when I can move it, it doesn't allow me to click on anything. The keyboard is also completely unresponsive, even though I can still sort of see the screen and move the cursor about.
The problem seems to build over time - when the problem occurs, I have to force a shut down and unless I give it 20 or so minutes, nothing will have changed when I reboot. If I wait a while, the screen will appear normal and I can successfully boot up but within 20 minutes the problem returns and freezes everything up.
I've tried zapping the PRAM, checked the HD (it had to be repaired, which I did this morning successfully - it checked out ok after that), shut off graphics switching (ironically when I did this, the problem started up immediately), and tried shutting off memory compression. Nothing has worked so far.
I'm going to try switching out the RAM for the original sticks next, and I noticed there is an update (10.9.3) available for download - I just don't know if I can even download it in the little time I have while the machine is working, before it decides to crash again. Most people on this forum seem to have a purely graphical error that doesn't necessarily freeze the machine, but once it happens for me, it's game over - have to force a shut down and put it away for a half hour. Any ideas or suggestions? Is this likely a hardware issue with the logic board and/or NVIDIA chip?