Index: branches/2.2/wp-includes/cache.php
===================================================================
--- branches/2.2/wp-includes/cache.php	(revision 5599)
+++ branches/2.2/wp-includes/cache.php	(working copy)
@@ -279,7 +279,7 @@
 			$data = '';
 
 		$this->cache[$group][$id] = $data;
-		unset ($this->non_existant_objects[$group][$id]);
+		@unset ($this->non_existant_objects[$group][$id]);
 		$this->dirty_objects[$group][] = $id;
 
 		return true;