I have tried doing that and the problem still persists.
Do you have a google toolbar or something?
Is the sound that you are hearing the same sound that is selected to play in the Sounds console within the Control Panel?
Or do you have different sounds selected but are getting these odd ones instead?
If that's the case, try playing the sound file you have selected from within a different sound player like Winamp or Windows Media Player so you can hear what that file actually sounds like. If they sound the way they should....I'm stumped. For now.