Comment 51 for bug 437429

Przemek K. (azrael) wrote :

Use the solution that I've mentioned earlier:

sudo -u gdm dbus-launch gconftool-2 --set /apps/gdm/simple-greeter/settings-manager-plugins/sound/active --type bool false

or:

sudo -u gdm dbus-launch gconftool-2 --set /desktop/gnome/sound/event_sounds --type bool false

The second one will disable sounds for the GDM user so it will not be changed by updates of GDM. It works for me.