[WP2.3.3] flash doesn’t display in subpages

I created a little plugin in order to display a flash animation (book.swf) in pages.
It is based on a filter on “the_content”.

Everything works in a page. Here is an exemple: http://blog.artwo.fr/wp/books

When I create a subpage, all is freezed (IE or firefox). Here is an example: http://blog.artwo.fr/books/san-francisco

The source code is exactly the same. If I take the same page but without parent page, it displays well.

If I take the source code and put it in a html file, it displays well.

Here is the filter:

function wp_books_filter($content) {
	global $wpdb;
	$plugin_path = get_settings('siteurl') ."/wp-content/plugins/wp_books/";
	$wp_books_flash_script = $plugin_path . 'swf/book.swf';

	if (eregi ("<!--WP_Books (:alnum:+) -->",$content,$reg)){
	$wp_books_xml_album = $plugin_path.'xml/'.$reg[1].'.xml';
	$wp_books_html='<div id="book" style="height:600px;">

	<object id="album" classid="clsid:D27CDB6E-AE6D-11cf-96B8-444553540000" width="100%" height="100%">
				<param name="movie" value="' . $wp_books_flash_script . '" />
				<param name="menu" value="false" />
                <param name="quality" value="high" />
				<param name="wmode" value="transparent" />
				<param name="flashvars" value="xmlFile=' . $wp_books_xml_album . '" />
        			<!--[if !IE]>-->
				<object type="application/x-shockwave-flash" data="' . $wp_books_flash_script . '" width="100%" height="100%">
				<param name="menu" value="false" />
                <param name="quality" value="high" />
				<param name="wmode" value="transparent" />
				<param name="flashvars" value="xmlFile=' . $wp_books_xml_album . '" />
				<!--<![endif]-->
		<h4>Books</h4>
		<p>Get <a href="http://adobe.com/go/getflashplayer">Flash player</a>.</p>
				<!--[if !IE]>-->
				</object>
				<!--<![endif]-->
			</object>
		</div>
	';
	$content = eregi_replace("<!--WP_Books (:alnum:+) -->", $wp_books_html, $content );

	}
	return $content;
	}