Index: wp-includes/default-widgets.php
===================================================================
--- wp-includes/default-widgets.php	(revision 12462)
+++ wp-includes/default-widgets.php	(working copy)
@@ -732,7 +732,9 @@
 			echo $before_title . $title . $after_title;
 		wp_widget_rss_output( $rss, $instance );
 		echo $after_widget;
-		$rss->__destruct(); 
+
+		if ( ! is_wp_error($rss) )
+			$rss->__destruct();
 		unset($rss);
 	}