Intermittent internal server error (500)

Hi.

I am trying to add new functionality to this site (powered by WP 3.4.2 and Thesis 1.8.2) via the custom_functions.php file.

Upon adding this code:

<?php if(is_home() && !is_paged()) { ?>
	<div id="featureditems">
		<h1 id="feat_title">Featured Case Studies</h1>
		<?php
		global $post;
		$args = array( 'numberposts' => '3', 'category' => '59' );
		$myposts = get_posts( $args );
		foreach( $myposts as $post ) :	setup_postdata($post); ?>
			<div class="featureditem">
				<a href="<?php the_permalink(); ?>"><div class="feattop">
					<h2><?php echo get_the_title(); ?></h2>
					<?php the_post_thumbnail('featured_thumb'); ?>
				</div></a>
				<div class="excerpt"><?php the_excerpt(); ?></div>
				<p class="more"><a href="<?php the_permalink(); ?>">+ full overview</a></p>
			</div>
			<?php endforeach; ?>
	<h1 id="explore_more">Explore More</h1>
	</div>
<?php } ?>

I now receive an internal server error every hundred or so pageloads.

The entire contents of custom_functions.php can be seen here.

Any insight is greatly appreciated.