Multiple query in header not display loop in post pages

Hi guys!
Well i have a problem designing my first wp theme…
The problem is that if i put a line like this in the header

<?php query_posts("category_name=category-name"); ?>
	    <?php while (have_posts()) : the_post(); ?>
	    	<li><a href="<?php the_permalink(); ?>" title="<?php the_title();?>"><?php the_title();?></a></li>
		<?php endwhile; ?>

the loop in the single.php or page.php or archive.php… in all of the page excluding the home (where i have only query_posts tags)… the loop don’t work…
Sorry but i’m a beginner and i don’t know which way to turn…