Windows 7 System Sounds

In Windows 7 Control Panel after clicking "Sound" I get a box with 4 tabs: "Playback" "Recording" "Sounds" and "Communications".
When I click on "Sounds" I am allowed to change the .wav file associated with various Program Events. Most work well such as those under "Windows Explorer". However none are working under "Windows". Such as "Close Program" or "Maximize" or "Minimize".
I tried modifying existing Schemes as well as creating new ones.
Has anyone else noticed this problem in Windows 7 or can offer a suggestion?