Starting last night, I started noticing graphics anomalies in-game. For example, parts of Purgatory were showing wire-frames. Some games had the problem, some didn't. This morning, I started up a practice match in Longest Yard and the sky is completely wire-framed. I haven't changed my config at all. This problem just appeared. It occurs in both Firefox and Safari for Mac OS X 10.8.2.
Any ideas what's causing this and how to fix it?
I've attached three screenshots, from Longest Yard, Purgatory, and Skyward: