I now see underground the map on all characters. I can see well over the horizon, but I will not see the ground, I see throught it, an endless blue color going deep under where the ground would be. I tried restarting and switching char, nothing works for now.
If the problem persists please turn down your graphics settings one by one in the options menu, starting with shadows and water settings. Some options will require you to restart the game.
I've been getting something similar but it's not all the time. Just when I tilt the 3rd person camera to a certain angle. I did recently update to the latest nVidia drivers offered by from EVGA (197.13) but when I find a spot where I see it again I'll try updating to nVidia's own latest driver (197.45).
I did Fraps it happening but since you already know about this issue I guess you don't need that.