Index: includes/menu.inc
===================================================================
RCS file: /cvs/drupal/drupal/includes/menu.inc,v
retrieving revision 1.279
diff -u -p -r1.279 menu.inc
--- includes/menu.inc	1 Jul 2008 20:36:40 -0000	1.279
+++ includes/menu.inc	5 Jul 2008 17:05:49 -0000
@@ -1718,7 +1718,6 @@ function menu_router_build($reset = FALS
       $menu = $cache->data;
     }
     else {
-      db_query('DELETE FROM {menu_router}');
       // We need to manually call each module so that we can know which module
       // a given item came from.
       $callbacks = array();
@@ -1734,7 +1733,6 @@ function menu_router_build($reset = FALS
       // Alter the menu as defined in modules, keys are like user/%user.
       drupal_alter('menu', $callbacks);
       $menu = _menu_router_build($callbacks);
-      cache_set('router:', $menu, 'cache_menu');
     }
   }
   return $menu;
@@ -2314,6 +2312,10 @@ function _menu_router_build($callbacks) 
   }
   array_multisort($sort, SORT_NUMERIC, $menu);
 
+  if ($menu) {
+    // Delete the existing router since we have some data to replace it.
+    db_query('DELETE FROM {menu_router}');
+  }
   // Apply inheritance rules.
   foreach ($menu as $path => $v) {
     $item = &$menu[$path];
@@ -2401,6 +2403,7 @@ function _menu_router_build($callbacks) 
   $masks = array_keys($masks);
   rsort($masks);
   variable_set('menu_masks', $masks);
+  cache_set('router:', $menu, 'cache_menu');
   return $menu;
 }