Comment 2 for bug 840660

StacktraceTop:
 users_service_dbus_can_activate_session (self=0x9a6cc00) at /build/buildd/indicator-session-0.3.4.2/./src/users-service-dbus.c:934
 user_menu_mgr_rebuild_items (self=0x9a6b880, greeter_mode=0) at /build/buildd/indicator-session-0.3.4.2/./src/user-menu-mgr.c:121
 g_cclosure_marshal_VOID__STRING (closure=0x9a727e8, return_value=0x0, n_param_values=2, param_values=0x9a44a78, invocation_hint=0xbfa86b10, marshal_data=0x0) at /build/buildd/glib2.0-2.29.18/./gobject/gmarshal.c:504
 g_closure_invoke (closure=0x9a727e8, return_value=0x0, n_param_values=2, param_values=0x9a44a78, invocation_hint=0xbfa86b10) at /build/buildd/glib2.0-2.29.18/./gobject/gclosure.c:774
 signal_emit_unlocked_R (node=0x9a62e98, detail=0, instance=0x9a6cc00, emission_return=0x0, instance_and_params=0x9a44a78) at /build/buildd/glib2.0-2.29.18/./gobject/gsignal.c:3272