PHP and IE5.5 download problem

Hi! I have a script which sends the following headers in order to get the client to display a "file save" prompt. > header ("Content-Type: application/octet-stream"); > header ("Content-Disposition: attachment; filename=$filename"); > readfile($filename); This works well on Netscape/lynx. However, IE 5.5 has a problem with this - I get a message saying that the "file could not be found". Looked around online, some sites say that this is an IE-specific issue with MIME-type recognition. However, I see sites like yahoo and deja allowing users to download email attachments using a similar technique, and that works fine on IE. Any ideas on what I'm doing wrong here? TIA! Vikram