you have output on the page at lines 1 and 2:
<![CDATA[@@OldIncludeCode@@]]>
<![CDATA[@@OldIncludeCode@@]]>
<?php require_once("webassist/security_assist/wa_md5encryption.php"); ?>
delete the code at line 1 and 2:
<![CDATA[@@OldIncludeCode@@]]>
<![CDATA[@@OldIncludeCode@@]]>