ramzes, допустим я изменил вот так
<?php
define('_IN_JOHNCMS', 1);
include "incfiles/core.php";
$last_id =$id;
$text = isset($_POST['text']) ? trim($_POST['text']) : '';
mysql_query("INSERT INTO `cms_news_comments` SET
`refid` = '$last_id',
`time` = '" . time() . "',
`user_id` = '" . $user_id . "',
`text` = '" . mysql_real_escape_string($text) . "';");
$_SESSION['error'] = '<div class="gmenu">' . $lng_news['added_message'] . '</div>';