Problem with loop on php5 only

I need a bit of help here guys so if anyone can see why this might be causing a problem, please give your thoughts. I’m willing to try anything.

Here’s the issue. The theme works perfect on php4, but as soon as I tried it on a host with php5 – I have a major problem in the search results page. Every result repeats 3 times.

So you understand where the $cat is coming from, this is in the search.php grabbing a variable passed from the previous page:
<?php $cat = $_GET["cityid"]; ?>

This is the full loop found lower in the search.php:

<?php if (have_posts()) : ?>
<h2>Here's what we found when we searched for:</h2>
<h3><?php the_search_query(); ?></h3>
  <div id="main-results">
<ol>
<?php while (have_posts()) : the_post(); ?>
<?php if ( in_category($cat) ) { ?> <!-- checks to make sure we're searching selected category only -->
<?php $url = get_post_meta($post->ID, 'url', $single = true); ?> <!-- get the meta value url -->
      <li><?php the_title(); ?> <span class="s-url"><a href="<?php echo $url; ?>" title="<?php the_title(); ?>"><?php echo $url; ?></a></li>
<?php } else { ?>
<div id="main-results">
<h2>No results found. Try a different search?</h2>
</div> <!-- /main-results -->
<?php } ?>
<?php endwhile; ?>
    </ol>
<?php if(function_exists('wp_pagenavi')) { wp_pagenavi(); } ?>
	</div> <!-- /main-results -->
<?php else : ?>
<div id="main-results">
<h2>No results found. Try a different search?</h2>
</div> <!-- /main-results -->
<?php endif; ?>

As I said, this works as expected on the server with PHP4. For some reason all my results are repeating 3 times each on the results page.

Any ideas?