Here's a strange one (at least to me): I did a reinstall of Win 7; the default Windows sounds work fine, even if I change the theme in the personalization options or in the Sounds control panel tab. But if I change a system sound to a .wav file from my own folder of custom sounds, Windows won't play it. Oh, by the way, they will play fine through Windows Media Player (or any other media player I've used--just not in the System Sounds function.
I've used these sounds many times before and my other computers running Windows 7 have been customized to use my sound files, but this one will not play them. I'm guessing I could reinstall Windows and they would probably work, but I really don't want to go to that extreme (yet). Any thoughts on why Windows won't use these substitute sounds?