Comment 57 for bug 437429

Work around "sudo -u gdm gconftool-2 --set /desktop/gnome/sound/event_sounds --type bool false" does NOT work.

Sorry, user (username) is not allowed to execute '/usr/bin/gconftool-2 --set /desktop/gnome/sound/event_sounds --type bool false' as gdm on (hostname).

But the line below does. So I edited the workaround above.

sudo su gdm -c "gconftool-2 --set /desktop/gnome/sound/event_sounds --type bool false"