XP MCE issue

I just did a new build of an MCE machine. I installed an ATI tuner card, but made the mistake of also installing the ATI theatre software. Now, when I try to play a DVD in Media Center, I get a decoder error telling me to exit Media Center and restart or restart the computer.

I know there is a decoder installed but Media Center isn’t “seeing” it. How can I best resolve this issue? BTW, the ATI Theatre software plays DVD fine.