Since a screenshot cant flicker to see what you are seeing, I can only state from prior video card issues that I have experienced what I think you may be seeing.
Is this happening in any other games or just this one?
Some games release bug fix patches, have you checked to see if there are any bug fix patches for this game and are you fully patched up?
I had an issue with a game called Dragon Age 2 with a flickering with GeForce GT 430 and patch v1.04 corrected this. Darkly shaded areas of the game would occasionally flicker white and back to dark shaded. This didnt happen when standing still in game, but only when moving around such as turning or running towards a dark shaded area. The flickering happened more frequently when turning left or right, but patch 1.04 fixed this game. All other games worked fine with the video card and latest nVidia drivers for the GT 430. For the fact that the problem was only with this one game, I knew that it was just something with this one game and not video card since all other games had no problems.
