Şöyle deneyin birde

function bul($bas, $son, $yazi)
{
@preg_match_all('/' . preg_quote($bas, '/') .
'(.*?)'. preg_quote($son, '/').'/', $yazi, $m);
return @$m[1];
}
$site = file_get_contents("http://wmaraci.com/forum/php.html");
$baslik = bul("id=\"thread_title_108593\" style=\"font-weight:bold\" >", "", $site);
echo $baslik[0];
?>