Comment 2 for bug 946124

StacktraceTop:
 gnome_rr_screen_get_dpms_mode (screen=0x0, mode=0xbfe6909c, error=0xbfe690ec) at gnome-rr.c:1157
 gnome_rr_screen_set_dpms_mode (screen=0x0, mode=GNOME_RR_DPMS_ON, error=0xbfe690ec) at gnome-rr.c:1241
 upower_notify_resume_cb (client=0x8ae3af0, sleep_kind=UP_SLEEP_KIND_SUSPEND, manager=0x8b13860) at gsd-power-manager.c:3611
 g_cclosure_marshal_VOID__UINT (closure=0x8b19d08, return_value=0x0, n_param_values=2, param_values=0x8bdf6a0, invocation_hint=0xbfe69240, marshal_data=0x0) at /build/buildd/glib2.0-2.31.18/./gobject/gmarshal.c:259
 g_closure_invoke (closure=0x8b19d08, return_value=0x0, n_param_values=2, param_values=0x8bdf6a0, invocation_hint=0xbfe69240) at /build/buildd/glib2.0-2.31.18/./gobject/gclosure.c:774