how to hide or customize webGUI error code?

From:	"cfs2" <cii633 at 21cn dot com>
To:	<m0n0wall at lists dot m0n0 dot ch>
Subject:	how to hide or customize webGUI error code?
Date:	Sat, 27 Dec 2003 22:41:52 +0800

when i visit a nonexistent web page,the ie show ;
404 Not Found
File not found. 
mini_httpd/1.17beta1 26may2002

hwo I hide the error code or customize own web page?