includes/menu.inc      |   30 ++++++++++++++----------------
 modules/menu/menu.test |    2 +-
 2 files changed, 15 insertions(+), 17 deletions(-)

diff --git includes/menu.inc includes/menu.inc
index 8e2fb1f..0f386a9 100644
--- includes/menu.inc
+++ includes/menu.inc
@@ -2639,24 +2639,22 @@ function menu_link_save(&$item) {
     }
   }
 
-  // If we have a parent link ID, we use it to inherit 'menu_name' and 'depth'.
+  // If this link defines a parent link id, try to find it in the current menu
+  // links. If found, we use it for the re-parenting process below. This parent
+  // link validation also needs to be done for links specifying a plid of 0
+  // (zero), since {menu_links} may contain stale/bogus data caused by a
+  // re-parenting process that went wrong in a previous rebuild.
   if (isset($item['plid'])) {
-    if ($item['plid']) {
-      $parent = db_query("SELECT * FROM {menu_links} WHERE mlid = :mlid", array(':mlid' => $item['plid']))->fetchAssoc();
-    }
-    // If the parent link ID is zero, then this link lives at the top-level.
-    else {
-      $parent = FALSE;
-    }
-  }
-  // Otherwise, try to find a valid parent link for this link.
-  else {
+    $parent = db_query("SELECT * FROM {menu_links} WHERE mlid = :mlid", array(':mlid' => $item['plid']))->fetchAssoc();
+  }
+  // If no plid was specified or it was not found, try to find a new, valid
+  // parent link for this link. Only do this if this is a menu link provided
+  // through hook_menu(). We can not guess the parent for menu items added
+  // through the UI or modules since we can not assume that they are parented
+  // by their path.
+  if (empty($parent) && $item['module'] == 'system') {
     $query = db_select('menu_links');
-    // Only links derived from router items should have module == 'system', and
-    // we want to find the parent even if it's in a different menu.
-    if ($item['module'] == 'system') {
-      $query->condition('module', 'system');
-    }
+    $query->condition('module', 'system');
     // We always respect the link's 'menu_name'; inheritance for router items is
     // ensured in _menu_router_build().
     $query->condition('menu_name', $item['menu_name']);
diff --git modules/menu/menu.test modules/menu/menu.test
index 3c99e26..45ca01a 100644
--- modules/menu/menu.test
+++ modules/menu/menu.test
@@ -576,7 +576,7 @@ class MenuNodeTestCase extends DrupalWebTestCase {
     // Change default parent item to Navigation menu, so we can assert more
     // easily.
     $edit = array(
-      'menu_parent' => 'navigation:0',
+      'menu_parent' => 'main-menu:0',
     );
     $this->drupalPost('admin/structure/types/manage/page', $edit, t('Save content type'));