--- includes/theme.inc	2009-05-28 12:44:05.000000000 -0400
+++ includes/themeNew.inc	2009-05-31 14:14:59.000000000 -0400
@@ -720,6 +720,8 @@ function theme() {
   }
 
   if (!isset($hooks[$hook])) {
+    $message = t("Drupal could not locate '@key' in the theme registry.", array('@key' => $hook));
+    watchdog('theme', $message, array(), WATCHDOG_WARNING);
     return;
   }