Problems with pagination in category.php

Have problems to get to page 2/3/4 etc with my categorys from the posts. I get error that the page is not found. The theme is homemade using WP 3.8 and Bootsrap 3.0 in the bottom.

I think the trouble is in line
$wp_query->query('showposts=1' . '&paged='.$paged . '&cat=' . $cat);

, any suggestions?

<?php get_header(); ?>
	<a href="../blogg/"><h1 class="tunn grey" style="clear: both;">Blogg</h1></a>

<div class="blogg col-xs-12 col-sm-10 col-md-10">

	<article>

		<?php // Display blog posts on any page @ https://m0n.co/l
		$temp = $wp_query; $wp_query= null;
		$wp_query = new WP_Query();
		$wp_query->query('showposts=1' . '&paged='.$paged . '&cat=' . $cat);
		while ($wp_query->have_posts()) : $wp_query->the_post(); ?>
        <div class="info col-xs-5 col-sm-2 col-md-2">
			<div class="blogdate col-xs-0 col-sm-0 col-md-0">
  				<p class="post-day"><?php the_time('j') ?> </p>
    			<p class="post-month"><?php the_time('F') ?> </p>
  				<p class="post-year"><?php the_time('Y') ?> </p>
			</div>
   		</div>
		<div class="post col-xs-12 col-sm-10 col-md-10"><h2><a>" title="L?s mer"><?php the_title(); ?></a></h2>
			<?php the_content(); ?>
                <div class="tunn"></div>
         </div>

			<?php endwhile; ?>

			<?php if ($paged > 1) { ?>

			<nav id="nav-posts">
				<?php wp_pagenavi(); ?>

			</nav>

			<?php } else { ?>

			<nav id="nav-posts" >
				<?php wp_pagenavi(); ?>
			</nav>

			<?php } ?>

		<?php wp_reset_postdata(); ?>

			</article>
</div>

<div class="blogg col-xs-12 col-sm-12 col-md-2 pull-right">
	<?php get_sidebar(); ?>
</div>