IE php header() error for program protocol

[m002.p]

Hi everyone,

I am having an interesting issue which is only apparent in IE and works in FireFox.

I have a form that depending on the submitted data with PHP either launches a link or does not.

The issue lies with the following:

<?php

if ($form == 'true')
{
header("Location: xfire:join?game={$g}&server={$s}:{$data_s['joinport']}&password={$pw}");
exit();
}
else
{
echo "error";
}


Obviously this link launches the xfire application and for some reason gives an IE error page

http://250kb.de/u/110104/j/QzVSrXyw5M4E.jpg

Any ideas? The header works ok with a normal http:// link but not with the xfire: protocol.

Thanks for your help in advance

Matt