Hi,
WP-Codebox works well for me.
But today I saw that if I use this chunk of code in a post:
<pre lang="php">global $page;
$pages = count( explode( '<!--nextpage-->', $wp_query->post->post_content ) );
if ($page) { echo ' | Pagina '.$page.' di '.$pages; }</pre>
WordPress executes the nextpage intead of being blocked from doing it.