Pagination using multiple loops?

Hi there, i have a doubt with the multple loops and pagination.

I try to use three loops but my prev and next links it does not work in any, gives back ‘ not found’.

If anybody can check this image perhaps it can explain to me better
https://img524.imageshack.us/my.php?image=helpwpjk6.png

My code for “the first” is this, here no prob, but I want show only the last post for the category 20.

<?php if (have_posts()) : // first post cat20 ?>
<?php $my_query = new WP_Query('cat=20&showposts=1'); ?>
<?php while ($my_query->have_posts()) : $my_query->the_post();
 $do_not_duplicate = $post->ID; ?>
<div id="post-<?php the_ID(); ?>" class="post firstpost">
<div class="entry">
<?php the_content('Continuar leyendo &raquo;'); ?>
</div>
</div>
<?php endwhile; ?>
<?php endif; ?>

Now Just below i add this:
And here is where the problem begins. I want to show the last 10 post for the category 1 and include the pagination… but pagination does not work ??

<div class="divider">
<div class="news">
<h2>Noticias</h2>
<?php query_posts($query_string . "&cat=1");
while (have_posts()) : the_post(); // loop continue the first post cat1 ?>
<div class="newpost">
<h2><a href="<?php the_permalink() ?>" rel="bookmark" title="<?php the_title(); ?>">
<?php the_title(); ?></a>
<?php edit_post_link('*', '<sup>', '</sup>'); ?></h2>
<?php the_content('Continuar leyendo...'); ?>
</div>
<?php endwhile; ?>
<div class="navigation"><?php posts_nav_link('','siguientes','anteriores'); ?></div>
</div>

Now the last part is :
I want to show only the last three post for the category 19 and I use a custom field (url_image) and here… the pagination not work again ??

If it is not possible that it’s in the two parts although is whereupon it works in this part would be perfect.

<div class="images">
<h2>Imagenes</h2>
<?php if (have_posts() ): ?>
<?php query_posts($query_string . "&cat=19");
while (have_posts()) : the_post(); //second loop ?>
<div class="themePreview" id="post-<?php the_ID(); ?>">
<?php $url_image = get_post_meta($post->ID, "url_image", $single = false); ?>
<a href="<?php the_permalink() ?>" rel="bookmark" title="<?php the_title(); ?>">
<?php foreach( $url_image as $url_image ) {
echo "<img class='tmb' src='".$url_image."' alt='' />";} ?>
</a>
</div>
<?php endwhile; ?>
<div class="navigation"><?php posts_nav_link('','siguientes','anteriores'); ?></div>
<?php else : ?>
<h2 class="center">Not Found</h2>
<p class="center">Sorry, but you are looking for something that isn't here.

<?php endif; ?>

Thank you very much for your time.

Atte: People Strange