Hmm something wrong

//
// Update posts, topics, last_post, last_post_id and last_poster for a forum (redirect topics are not included)
// If $transaction == PUN_TRANS_END, this function will end the current transaction
//
function update_forum($forum_id, $transaction = 0)
{
    global $db;

    $result = $db->query('SELECT COUNT(id), SUM(num_replies) FROM '.$db->prefix.'topics WHERE moved_to IS NULL AND forum_id='.$forum_id) or error('Unable to fetch forum topic count', __FILE__, __LINE__, $db->error());
    list($num_topics, $num_posts) = $db->fetch_row($result);

    $num_posts = $num_posts + $num_topics;        // $num_posts is only the sum of all replies (we have to add the topic posts)

    $result = $db->query('SELECT last_post, last_post_id, last_poster, subject FROM '.$db->prefix.'topics WHERE forum_id='.$forum_id.' AND moved_to IS NULL ORDER BY last_post DESC LIMIT 1') or error('Unable to fetch last_post/last_post_id/last_poster', __FILE__, __LINE__, $db->error());
    if ($db->num_rows($result))        // There are topics in the forum
    {
        list($last_post, $last_post_id, $last_poster) = $db->fetch_row($result);

        $db->query('UPDATE '.$db->prefix.'forums SET num_topics='.$num_topics.', num_posts='.$num_posts.', last_post='.$last_post.', last_post_id='.$last_post_id.', last_poster=\''.addslashes($last_poster).'\', subject=\''.addslashes($subject).'\' WHERE id='.$forum_id, $transaction) or error('Unable to update last_post/last_post_id/last_poster', __FILE__, __LINE__, $db->error());
    }
    else    // There are no topics
        $db->query('UPDATE '.$db->prefix.'forums SET num_topics=0, num_posts=0, last_post=NULL, last_post_id=NULL, last_poster=NULL, subject=NULL WHERE id='.$forum_id, $transaction) or error('Unable to update last_post/last_post_id/last_poster', __FILE__, __LINE__, $db->error());
}

// Print the categories and forums
$extra_sql = ($cur_user['status'] < PUN_MOD) ? ' WHERE f.admmod_only=\'0\'' : '';

$result = $db->query('SELECT c.id AS cid, c.cat_name, f.id AS fid, f.forum_name, f.forum_desc, f.moderators, f.num_topics, f.num_posts, f.last_post, f.last_post_id, f.last_poster, f.closed, f.subject FROM '.$db->prefix.'categories AS c INNER JOIN '.$db->prefix.'forums AS f ON c.id=f.cat_id'.$extra_sql.' ORDER BY c.disp_position, c.id, f.disp_position') or error('Unable to fetch category/forum list', __FILE__, __LINE__, $db->error());

while ($cur_forum = $db->fetch_assoc($result))
{
    if ($cur_forum['cid'] != $cur_category)    // A new category since last iteration?
    {


AND THIS

// If there is a last_post/last_poster. 
    if ($cur_forum['last_post'] != '')
        $last_post = '<a href="viewtopic.php?pid='.$cur_forum['last_post_id'].'#'.$cur_forum['last_post_id'].'">
<img src="'.$pun_config['o_styleimg_dir'].'/lastpost.gif" alt="ostatni post" border="0" align="middle" ></a> '.format_time($cur_forum['last_post']).'<br><b>'.$lang_common['by'].'</b> '.pun_htmlspecialchars($cur_forum['last_poster']).'</br><b>'.$lang_common['in'].'</b>  <span class="postdetails">'.pun_htmlspecialchars($cur_forum['subject']).'</span>';
    else
        $last_post = '<b>'.$lang_common['by'].'</b></br><b>'.$lang_common['in'].'</b>';