Index: wp-includes/default-filters.php
===================================================================
--- wp-includes/default-filters.php	(revision 18544)
+++ wp-includes/default-filters.php	(working copy)
@@ -60,7 +60,8 @@
 foreach ( array( 'pre_comment_author_url', 'pre_user_url', 'pre_link_url', 'pre_link_image',
 	'pre_link_rss', 'pre_post_guid' ) as $filter ) {
 	add_filter( $filter, 'wp_strip_all_tags' );
-	add_filter( $filter, 'esc_url_raw'       );
+	if ($filter != 'pre_post_guid')
+		add_filter( $filter, 'esc_url_raw'       );
 	add_filter( $filter, 'wp_filter_kses'    );
 }