Multiple Loops pagination problem with custom permalinks

This is the code:

<?php
get_header();
# get_sidebar();
?>

     	<?php
			$category_id = get_the_category();
    		$category_link = get_category_link( $category_id[0]->cat_ID );
			$category = $category_id[0]->cat_ID;
		?>

          <div id="ContentFrame">
		  <!-- Single.php -->

      		<?php global $query_string;
			query_posts( $query_string . "&cat=$category&showposts=1" ); ?>

			<?php while (have_posts()) : the_post(); $src = wp_get_attachment_image_src( get_post_thumbnail_id($post->ID), array( 800,9999 ), false ); ?>

           <div class="stage">
		   <div id="Close">

               <a href="<?php echo $category_link; ?>" title="Zur&uuml;ck zur Rubrik"><img src="<?php bloginfo('template_url'); ?>/images/close-x.jpg" width="25" alt="Close"/></a>
		   </div>
		   <center><?php echo wpop_image_display(); ?></center>
           </div> <!-- end .stage -->
			<?php endwhile; ?>
		   <div class="navigation">
				<div class="nav_alignright">
				<?php previous_post_link('%link','&raquo;&raquo;', TRUE); ?>
                    </div>  

				<div class="nav_alignleft">
				<?php next_post_link('%link','&laquo;&laquo;', TRUE); ?>
                </div>
          	</div>	

		<center>

		<?php

		$cat = $category;
		$post_per_page = 8; // -1 shows all posts
  		$do_not_show_stickies = 1; // 0 to show stickies
  		$args=array(
    		'category__in' => array($cat),
    		'orderby' => 'date',
    		'order' => 'DESC',
    		'paged' => $paged,
    		'posts_per_page' => $post_per_page,
    		'caller_get_posts' => $do_not_show_stickies
  		);

  		$temp = $wp_query;  // assign orginal query to temp variable for later use
  		$wp_query = null;
  		$wp_query = new WP_Query($args);
  		?>

		<div id="ImageSelection">
        <ul id="ImgRow">
        <?php // echo $paged; ?>

		<?php if( have_posts() ) :
			while ($wp_query->have_posts()) : $wp_query->the_post(); ?>

    		<li><a href="<?php echo the_permalink(); ?>"><?php echo get_the_post_thumbnail($post->ID, 'thumbnail'); ?></a></li>

		<?php endwhile;  ?>

          </ul>

          </div> <!-- end of ImageSelection -->
          </center>
          <center>
          	<div class="ImgNavi">
      			<div class="ImgNaviLeft"><?php previous_posts_link('&laquo;&laquo;') ?></div>
				<div class="ImgNaviRight"><?php next_posts_link('&raquo;&raquo;') ?></div>
    			</div>
  		</center>
		<?php else : ?>

		<center>
		<h2 class="center">Not Found</h2>
		<p class="center">Sorry, but you are looking for something that isn't here.</p>
		</center>

		<?php endif; ?>

		</div> <!-- end of ContenFrame -->				

<?php get_footer(); ?>

Good morning again,
I think today is the perfect day to be helped out here in the forum by somebody.