Welcome to the forums.
First off you want dirctex turned on, that option is there for people who want to make applications instead of games.
Chances are that even though you have DirectX 9, you probably don't have the most current version.
Windows does not update that automatically.
You easiest fix right now is to run the installer again, and say yes to any windows that pop up... although the dx9 window gets hidden sometimes.
If that still doesn't fix it then you might try updating your video drivers, and make sure they can at least handle level 1 shaders.