Index: wp-admin/includes/ms.php
===================================================================
--- wp-admin/includes/ms.php	(revision 21474)
+++ wp-admin/includes/ms.php	(working copy)
@@ -111,6 +111,7 @@
 					else if ( @is_file( $dir . DIRECTORY_SEPARATOR . $file ) )
 						@unlink( $dir . DIRECTORY_SEPARATOR . $file );
 				}
+				@closedir( $dh );
 			}
 			$index++;
 		}