I think it was caused by being left on too long. At least I hope so. I have no actual evidence one way or the other. I'm hoping the sleep fix in the latest firmware will address it.
Windows 7 x64
i5 2500K @4.6Ghz
8GB DDR3 1600
Nvidia GTX 660Ti
i5 2500K @4.6Ghz
8GB DDR3 1600
Nvidia GTX 660Ti
