Why does Zoom Player say it is "Unable to initialize the DirectShow interface" ?

While Zoom Player is designed to be backward compatible with older windows versions, there are certain features that absolutely require a specific version of DirectX to be installed.

For DVD Playback, you must have DirectX v8 or newer installed. For Media playback, you must have DirectX v5 installed, but v7 or newer is recommended.

VMR9 Support requires DirectX v9.