Both Penumbra episode giving vertex shader errors 8800GTX.

[GanjaStar]

Hello all,
I have an 8800GTX with the latest drivers installed from ASUS (169.21) and Penumbra: Overture AND Penumbra: Black Plague give me the error at startup that my graphics card does not support vertex shaders. I just got these games so I would really like to play them and any help would be greatly appreciated My OS is Windows XP Pro if it helps and I did patch the games. Thank you for any help...

I have the same card and both games work flawlessly, try 174.31 drivers. And Do not touch shader options in riva tuner if you did that.