Because no charset specify for the html page befor echo DISABLED_REASON,when administrator specify a No-english massage as the DISABLED_REASON,the browser will just display the page in ISO-8859-15 and no one can read the massage.
I just modify the code to echo MY OWN charset,may be there is a better way to do it.
/* before we go on, we need to do some very basic activation checks */
if (!($FUD_OPT_1 & 1)) {
//rhinofly
header("Content-type: text/html; charset=UTF-8");
fud_use('errmsg.inc');
exit($DISABLED_REASON . __fud_ecore_adm_login_msg);
}