Mapserver Displays Incorrect Image, Help!

[David Horowitz]

Thanks for the tips.  To prevent browser caching, I added the following
code to my PHP script which runs the map:

<?php
    header( "Expires: Mon, 20 Dec 1998 01:00:00 GMT" );
    header( "Last-Modified: " . gmdate("D, d M Y H:i:s") . " GMT" );
    header( "Cache-Control: no-cache, must-revalidate" );
    header( "Pragma: no-cache" );
?>

This code should force the browser to request a new image from mapserver
on each page load.  Unfortunately, this did not help the situation.  I
continue to see incorrect images when my pages load.  What is very odd
is that the problem only occurs on a Linux box (Redhat 9) and not on an
identical installation on my Windows machine.

Any help would be appreciated.

Thanks again,
David