Index: yelp/src/yelp-window.c
===================================================================
--- yelp/src/yelp-window.c	(revision 3119)
+++ yelp/src/yelp-window.c	(working copy)
@@ -1057,6 +1057,16 @@ yelp_window_load (YelpWindow *window, co
 		gint status = 0;
 		GError *error = NULL;
 
+		/* disallow external links when running in the GDM greeter session */
+		if (g_getenv ("RUNNING_UNDER_GDM") != NULL) {
+		    gchar *message = g_strdup_printf (_("The requested URI \"%s\" is invalid"), trace_uri);
+
+		    window_error (window, _("Unable to load page"), message, FALSE);
+		    g_free (message);
+
+		    return;
+		}
+
 		priv->base_uri = g_strdup ("file:///fakefile");
 
 		cmd = g_strdup_printf ("gnome-open %s", uri);