Windows Event Sounds Do Not Play

Some of my Windows sound scheme sounds do not play. In the sound scheme settings, under Program Events ,regardless of sound scheme selected, the Sound events for Windows DO NOT play, but sound events for Windows Explorer, and every single other application, DO play. When I click Test, the sound always plays, but in practice, never does. This only happens with the sound events under the Windows category� everything else plays fine. I�ve tried changing the sounds around (using different sound files), and it�s not the sound files themselves, my sound drivers, or anything like that. I�ve tried checking the registry, and that seems to be set up correctly. I�ve tried creating a new user profile, and it has the same problem. If you redirect me to a thread about similar problems, chances are, I�ve already read it if it�s easily found by a Google search. Not everyone has had the same exact problem anyway (where it plays when I click Test and only the Windows events are affected). Please don�t tell me to re-format, re-install, or repair Windows.