Have you donwloaded latest drivers from ATI??? It requires direct x 8.0a and the microsoft video update (both linked there)...it fixed my problems...
What OS??? I am using winme...
I am also using a GF2 pro with ref 22.40drivers...check settings under video overlay they have a check mark you can hit if having problems with tv card...
Also check cable and make sure it is good...connection and such...make sure no bad splice jobs...