Index: taxonomy.admin.inc
===================================================================
--- taxonomy.admin.inc	(revision 719)
+++ taxonomy.admin.inc	(working copy)
@@ -292,6 +292,10 @@
     $tree = taxonomy_get_tree($vocabulary->vid);
     $term = current($tree);
     do {
+      if ($must_prev) {
+        $term = prev($tree);
+        $must_prev = FALSE;
+      }
       // In case this tree is completely empty.
       if (empty($term)) {
         break;
@@ -314,7 +318,12 @@
           $before_entries--;
           $back_peddle++;
           if ($pterm->depth == 0) {
-            prev($tree);
+            if (key($tree) != 0) {
+              prev($tree);
+            }
+            else {
+              $must_prev = TRUE;
+            }
             continue 2; // Jump back to the start of the root level parent.
           }
         }