Player screen is blank on TV

[pc_user]

I am using the TV out on my ATI all-in-wonder card. I can see my computer screen on the TV. However when I used media player or real player to play a movie clip. It only shows blank screen on my TV. I can see the movie playing on my PC screen. For example, I have real player in windows mode (i.e. it only occupies a corner of my PC screen) When I player the movie clip, I can see it on my PC screen OK. But on the TV it is blank within the player. The rest of my desktop shows on the TV with no problem.
This happens in full screen mode also. I can see the player control buttons. But the player screen is blank. Any Idea ?

I have a note book computer which also has the S-Video out. I got he same problem too. This make me feel that it is not the ALL-in wonder card. It must be some kind of set up or driver problem.
I have my display down to 800X600 in both the PC and the notebook. It does not go any lower.

[Enchanter]

Enable Theatre Mode from under the Advanced Display settings.

[pc_user]

Please excuse my ignorance. Do you mean advance display setting under "contol panel/display" ? or advance display setting under media player or real player ? I looked everywhere and can not find theatre mode that you are referring to.

[Enchanter]

Look under Control Panel -> Display -> Advanced. I believe Theatre Mode can be found from under the Overlay tab (that is if you have the ATI Control panel installed; otherwise you need to install it first).