Index: includes/menu.inc
===================================================================
RCS file: /cvs/drupal/drupal/includes/menu.inc,v
retrieving revision 1.80
diff -u -r1.80 menu.inc
--- includes/menu.inc	24 Apr 2005 16:34:32 -0000	1.80
+++ includes/menu.inc	5 May 2005 23:13:42 -0000
@@ -969,10 +969,12 @@
     if (!isset($item['pid'])) {
       // Parent's location has not been customized, so figure it out using the path.
       $parent = $item['path'];
-      do {
-        $parent = substr($parent, 0, strrpos($parent, '/'));
+
+      if ($parent) {
+        while ($parent && !array_key_exists($parent, $_menu['path index'])) {
+          $parent = substr($parent, 0, strrpos($parent, '/'));
+        }
       }
-      while ($parent && !array_key_exists($parent, $_menu['path index']));
 
       $pid = $parent ? $_menu['path index'][$parent] : 1;
       $_menu['items'][$mid]['pid'] = $pid;