Co-authors plus problems with query_post

I had a query_post that worked, aimed lists only posts by author own, but now that I updated wordpress stopped working.

The query_post only works when you have only one author.

I updated WordPress 3.2.1. to 3.7.1

Index.php

<?php $post_count = 0; ?>
<?php get_header(); ?>

<div class="page">
<?php if (have_posts()) : ?>
<?php 
    if ($user_level == '1'){ 
        global $current_user;
        get_currentuserinfo();
        query_posts("author=$current_user->ID&showposts=4&paged=$paged"); 
    } 
?>
<div id="main">
        <ul id="navigationMenu">
            <li>
                <?php $walker = new Menu_With_Description; ?>
                <?php wp_nav_menu( array( 'theme_location' => 'content-menu', 'menu_class' => 'nav-menu', 'walker' =>  $walker ) ); ?>
            </li>
        </ul>
</div>
<div class="title-s">Posts</div>
        <?php while (have_posts()) : the_post(); ?>

            <div <?php post_class(); ?> id="post-<?php the_ID(); ?>">
                <p class="contador-comentario">
                <?php comments_popup_link( '0', '1', '%', 'comments-link', 'Comments are off for this post');?>
                </p>
                <div class="title-s">
                <h2><a href="<?php the_permalink() ?>" rel="bookmark" title="<?php printf(__('Post: %s', 'kubrick'), the_title_attribute('echo=0')); ?>"><?php the_title(); ?></a></h2>
                </div>
                <div class="resume">
                <?php the_excerpt() ?>
                </div>
            </div>
        <?php $post_count++; endwhile; ?>

<?php if ($post_count == '0' and $user_level == '1'){ 
        echo 'tour';
        echo $post_count;
        } ?>    

        <div id="nav-below" class="navigation">
            <div class="nav-previous"><?php next_posts_link( __( '<span class="meta-nav">&larr;</span> Older posts', 'twentyten' ) ); ?></div>
            <div class="nav-next"><?php previous_posts_link( __( 'Newer posts <span class="meta-nav">&rarr;</span>', 'twentyten' ) ); ?></div>
        </div><!-- #nav-below -->

        <?php else : ?>
        <h2 class="center"><?php _e('Not Found', 'kubrick'); ?></h2>
        <p class="center"><?php _e('Sorry, but you are looking for something that isn’t here.', 'kubrick'); ?></p>
        <?php get_search_form(); ?>
    <?php endif; ?>
</div><br>
<?php get_footer(); ?>