Tente isso para dissociá-lo:
sudo mv /usr/share/dbus-1/services/org.freedesktop.Notifications.service /usr/share/dbus-1/services/org.freedesktop.Notifications.service.disabled
para ativar novamente:
sudo mv /usr/share/dbus-1/services/org.freedesktop.Notifications.service.disabled /usr/share/dbus-1/services/org.freedesktop.Notifications.service