wordpress cat relative post query

 <?php $orig_post = $post;
global $post;
$categories = get_the_category($post->ID);
if ($categories) {
$category_ids = array();
foreach($categories as $individual_category) $category_ids[] = $individual_category->term_id;
$args=array(
'category__in' => $category_ids,
'post__not_in' => array($post->ID),
'posts_per_page'=> 5, // Number of related posts that will be displayed.
// 'caller_get_posts'=>1,
// 'orderby'=>'rand' // Randomize the posts
);

$my_query = new wp_query( $args );
if( $my_query->have_posts() ) {
while( $my_query->have_posts() ) {
$my_query->the_post(); ?>

<?php the_title(); ?> // for checking
<hr> // for checking

<? }
} }

$post = $orig_post;
wp_reset_query(); ?>

Please use this query for related post (I mean second query on your code)