This has come up a couple of times (although not for a long while); it seemed to be a graphics driver bug. Try upgrading to the most recent driver for your video card (or, if you have upgraded recently, try rolling back to the previous version).
This has come up a couple of times (although not for a long while); it seemed to be a graphics driver bug. Try upgrading to the most recent driver for your video card (or, if you have upgraded recently, try rolling back to the previous version).