Subcategories, pages & hihlighting

Hi, i’m using WP as a CMS but having some troubles.

First of all, my page navigation:

wp_list_pages('sort_column=menu_order&depth=1&title_li=&exclude=37');

I’ve got a page called articles. In page.php i’ve got some code to get in that page only the articles category posts:

if( is_page('articles') ) query_posts('category_name=articles');

In the sidebar.php i’ve got some code too, to show only the articles (ID=1) subcategories:

$this_cat = get_category($cat);
if( is_page('articulos') || is_category('articulos') || $this_cat->category_parent == 1 ) :
<ul>
wp_list_categories('title_li=&orderby=ID&show_count=0&use_desc_for_title=0&hide_empty=0&child_of=1');
</ul>
endif;

Th problem starts now, when i go to the page articles and then to some subcategory. The page li loses his .current_page_item and even if go to a post from there, the .current-cat dissappears too…

Any solution? TIA.