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I'm running this on Linux. I was playing just fine but suddenly I got this weird graphical bug.
I have seen this glitch before.

This is caused by anti aliasing being forced by the graphics card.

I remember reading something about AA when gaming on newer systems/OS's causing similar artifacts. One reason was that Win 7+ (I think) sometimes does not apply AA correctly for some games, since it may interpret them as running in a "Window." (Applies to windowed games, mostly, but could apply to others.) It will apply the AA to the desktop, but will bugger up some things it interprets are running in a separate window.

This is usually due to Aero theme issues, from what I've read. So, if you want AA, try messing around with disabling the Aero theme while playing games where you're having artifacts caused by AA routines.

Disabling the AA at the NVidi CP resolves the issue.