Index: template.php
===================================================================
--- template.php	(revision 15489)
+++ template.php	(working copy)
@@ -2893,8 +2893,15 @@
 	if ( !isset($wp_meta_boxes[$page][$context]) )
 		$wp_meta_boxes[$page][$context] = array();
 
-	foreach ( array('high', 'core', 'default', 'low') as $priority )
-		$wp_meta_boxes[$page][$context][$priority][$id] = false;
+	$flag = false;
+	foreach ( array('high', 'core', 'default', 'low') as $priority ) {
+		if ( isset($wp_meta_boxes[$page][$context][$priority][$id]) ) {
+			$wp_meta_boxes[$page][$context][$priority][$id] = false;
+			$flag = true;
+		}
+	}
+	
+	return $flag;
 }
 
 /**