I am going to guess you might have an Intel video chip. If that is the case, simply go into the game's "Video Settings" and either save the information, or change the "Maximum Texture Size" to 256 and see if that fixes it.
This all assumes you have an Intel video chip. If not, then could you email the output of the DXDIAG (Start->Run->DXDIAG) utulity to me?