I would like a screenshot for the sole reason of pleasing the game developer in me. I've never seen this and I've been playing since CB3.

But, it sounds like corruption; be it file (game or driver) or network (packets). After doing what Grit suggested, and if it doesn't work, try reinstalling the game and/or using a different NIC/cable? (could try updating chipset drivers too). Although, that'd be partially irrelevant to it working on the integrated GPU; but it's worth a try.

If that fails, you may have a bad video card; or it's ATI's drivers on your system causing an issue.