Looked like that for me too. Didn't think much of it at the time, since I'd been fiddling about with my graphics settings just a few minutes earlier. I have no idea what half the things I can turn on or off are for, or whether or not my graphics card supports them, so I figured I'd just loused something up myself. Slightly reassuring to know it's not just me.
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Seriously, I recently did Devil's Choice with a friend who has a completely different machine and we both had this bug as well.