I can't play Civ4 anymore!!!!

[CivLuvah]

I've installed a new webcam on my computer. After that, I can't open Civ 4: BTS because when I opened them, this message pops up that I need to install DirectX on my computer, but I already have DirectX on my computer.

Thinking that I need to update my DirectX, I downloaded the latest version, and it still doesn't work. What should I do?

Please help!!!!