Flickering Graphics - can hear the in-game sounds/music but completely unplayable

I have an NVIDIA GeForce 9800 GX2.

I have attempted to reinstall all new drivers for this Video Card, as well as sound, and DirectX drivers.  I have a logitec mouse and keyboard, which I have deactivated the software for as I saw others have had issues with that.  I have also attempted to delete and reinstall the game.  (I downloaded the game online.)  I have attempted to find anyone else describing this same issue, however, nothing similar found in the 18 pages of this forum.  I am able to play other games right now, like Age of Conan, and World of Warcraft with no graphical issues, so I don't think my graphics card is damaged.

The flickering I am getting is basically like big grey rectangles accross my screen, that flicker... moving up and down the screen.  EDIT: I am able to see the Demigod logo on loadup right before the flickering... the mouse icon changes to the in game mouse icon... and I can hear it "click" menu options.

Anyone have the same issue or a possible solution?  Thanks!