Depends on your PC, if you have a good configuration you can use on dx9. But if you use on dx7 you will notice that the graphic quality will be reduced significantly.
Thanks for all your suggestions!
I also have my game at the highest graphics. Will reduce my game to medium.
I also had flashing polygons during qualifying. Have not seen it before.
David, it happened to me also, with nvidia card and Win7 64bit.