Pagination – error 404 on page 2

Hello everyone,

I know there’ve been a lot of such posts, however, I couldn’t find a solution to my problem.
As the topic says, when I click on next page I get a 404 error.

I don’t know what is wrong with my code, because I’ve only copied it from my other website, where it works fine!

The code:

<?php
		$news = $wp_query;
		$wp_query = null;
		$wp_query = new WP_Query();
		$wp_query->query('showposts=4'.'&paged='.$paged);
		?>
		<?php if (have_posts()) : ?>
  		<?php while (have_posts()) : the_post(); ?>

		<hr>
		<h2><?php the_title(); ?></h2>
		<p><?php the_content(); ?></p> 

		<?php endwhile; ?>
		<?php else : ?>
		... no posts.
		<?php endif; ?>

		<div class="navigation">
		<div class="prev"><?php previous_posts_link('? Previous') ?></div>
		<div class="next"><?php next_posts_link('Next ?') ?></div>
		</div>

		<?php $wp_query = null; $wp_query = $myqueryname;?>