Index: includes/common.inc
=========================================================
--- includes/common.inc	(revision 1.1134)
+++ includes/common.inc	Fri Mar 26 23:04:28 EDT 2010
@@ -5311,7 +5311,7 @@
   $children = array();
   $sortable = FALSE;
   foreach ($elements as $key => $value) {
-    if ($key[0] !== '#') {
+    if ($key !== '' || $key[0] !== '#') {
       $children[$key] = $value;
       if (is_array($value) && isset($value['#weight'])) {
         $sortable = TRUE;