Index: wp-includes/feed-rss2-comments.php
===================================================================
--- wp-includes/feed-rss2-comments.php	(revision 23297)
+++ wp-includes/feed-rss2-comments.php	(working copy)
@@ -47,7 +47,7 @@
 			}
 		?></title>
 		<link><?php comment_link() ?></link>
-		<dc:creator><?php echo get_comment_author_rss() ?></dc:creator>
+		<dc:creator><![CDATA[<?php echo get_comment_author_rss() ?>]]></dc:creator>
 		<pubDate><?php echo mysql2date('D, d M Y H:i:s +0000', get_comment_time('Y-m-d H:i:s', true, false), false); ?></pubDate>
 		<guid isPermaLink="false"><?php comment_guid() ?></guid>
 <?php if ( post_password_required($comment_post) ) : ?>