Index: includes/menu.inc
===================================================================
RCS file: /cvs/drupal/drupal/includes/menu.inc,v
retrieving revision 1.407
diff -u -p -r1.407 menu.inc
--- includes/menu.inc	23 Aug 2010 23:38:06 -0000	1.407
+++ includes/menu.inc	31 Aug 2010 16:46:06 -0000
@@ -415,6 +415,9 @@ function menu_get_item($path = NULL, $ro
     $original_map = arg(NULL, $path);
     $parts = array_slice($original_map, 0, MENU_MAX_PARTS);
     $ancestors = menu_get_ancestors($parts);
+    if (empty($ancestors)) {
+      return FALSE;
+    }
 
     // Since there is no limit to the length of $path, use a hash to keep it
     // short yet unique.