Comment 6 for bug 872824

From the duplicate I just filled on an up to date 12.04 install:
stgraber@castiana:~$ nm-connection-editor
** WARNING **: Invalid setting VPN: remote
** WARNING **: Invalid setting VPN: remote
** WARNING **: Invalid setting VPN: remote
GLib-GObject-WARNING **: cannot register existing type `GtkWidget'
GLib-GObject-CRITICAL **: g_type_add_interface_static: assertion `G_TYPE_IS_INSTANTIATABLE (instance_type)' failed
GLib-GObject-WARNING **: cannot register existing type `GtkBuildable'
GLib-GObject-CRITICAL **: g_type_interface_add_prerequisite: assertion `G_TYPE_IS_INTERFACE (interface_type)' failed
GLib-CRITICAL **: g_once_init_leave: assertion `result != 0' failed
GLib-GObject-CRITICAL **: g_type_add_interface_static: assertion `G_TYPE_IS_INSTANTIATABLE (instance_type)' failed
GLib-GObject-CRITICAL **: g_type_register_static: assertion `parent_type > 0' failed
GLib-CRITICAL **: g_once_init_leave: assertion `result != 0' failed
GLib-GObject-CRITICAL **: g_type_register_static: assertion `parent_type > 0' failed
GLib-CRITICAL **: g_once_init_leave: assertion `result != 0' failed
GLib-GObject-CRITICAL **: g_type_get_qdata: assertion `node != NULL' failed
GLib-GObject-CRITICAL **: g_type_set_qdata: assertion `node != NULL' failed
GLib-GObject-CRITICAL **: g_type_get_qdata: assertion `node != NULL' failed
GLib-GObject-CRITICAL **: g_type_get_qdata: assertion `node != NULL' failed
GLib-GObject-CRITICAL **: g_type_set_qdata: assertion `node != NULL' failed
GLib-GObject-CRITICAL **: g_type_get_qdata: assertion `node != NULL' failed
GLib-GObject-WARNING **: cannot register existing type `GtkWidget'
GLib-GObject-CRITICAL **: g_type_add_interface_static: assertion `G_TYPE_IS_INSTANTIATABLE (instance_type)' failed

That's when opening nm-connection-editor and trying to add a strongswan IPSEC VPN, I confirmed that selecting another VPN type doesn't freeze the UI.