podpress posts do not display anymore.

All of sudden I’ve started getting this error when trying to open a single post that has a podpress element. Seems to have corresponded with the theme update.

Catchable fatal error: Object of class WP_Error could not be converted to string in /hermes/waloraweb060/b1755/pow.thesheep/htdocs/wp-content/themes/responsive/core/includes/functions.php on line 576

Here is where 576 is (its the $cats = str_replace('<a', $linkBefore . '<a' . $linkAttr, $cats); line)

} elseif ( is_attachment() ) {
			$parent = get_post($post->post_parent);
			$cat = get_the_category($parent->ID); $cat = $cat[0];
			$cats = get_category_parents($cat, true, $delimiter);
			$cats = str_replace('<a', $linkBefore . '<a' . $linkAttr, $cats);
			$cats = str_replace('</a>', '</a>' . $linkAfter, $cats);
			echo $cats;
			printf($link, get_permalink($parent), $parent->post_title);
			if ($showCurrent == 1) echo $delimiter . $before . get_the_title() . $after;

Any help would be great. Thanks.