problem with pdf serializing under cocoon 2.1.4

[MicFra]

hi,

i got a little problem with pdf-serializing after updating from
cocoon 2.1.2 to 2.1.4.

following scenario:
- using serializer org.apache.cocoon.serialization.FOPSerializer, with
name fo2pdf and mime-type application/pdf
- using it in

<map:match pattern="*/**/content.pdf">
<map:generate ... />
<map:transform src="templates/fo/standard.xsl" />
<map:serialize type="fo2pdf" />
</map:match>

so far, no problem because the document is delivered correctly with
firefox - but in IE, the pdf is not displayed. first he shouts
file is of unknown type - i opened it anyway - then he shouts
document could not be sent...

i tried to figure out what it is realy all about, but
even the sample of the cocoon project didn't work with
IE, http://localhost:8888/samples/fop/hello.pdf

so does anyone has an idea what is wrong - maybe an
installation problem

thanks a lot for information

further information:
- IE version: 6.0.2800.1106 under winXP
- HTTP Header of request-answer under firefox

GET http://..../content.pdf HTTP/1.1
Host: 127.0.0.1
User-Agent: Mozilla/5.0 (Windows; U; Windows NT 5.1; de-DE; rv:1.6)
Gecko/20040206 Firefox/0.8
Accept: application/x-shockwave-flash,text/xml,application/xml,application/xhtml+xml,text/html;q=0.9,text/plain;q=0.8,video/x-mng,image/png,image/jpeg,image/gif;q=0.2,*/*;q=0.1
Accept-Language: de-DE,de;q=0.8,en-us;q=0.5,en;q=0.3
Accept-Encoding: gzip,deflate
Accept-Charset: ISO-8859-1,utf-8;q=0.7,*;q=0.7
Keep-Alive: 300
Connection: keep-alive

HTTP/1.x 200 OK
X-Cocoon-Version: 2.1.4
Vary: Host, Host, Host, Host, Host, Host, Host, Host, Host, Host,
Host, Host, Host, Host, Host, Host, Host, Host, Host, Host, Host, Host
Content-Type: application/pdf
Content-Length: 7454
Date: Mon, 29 Mar 2004 17:15:04 GMT
Server: Apache-Coyote/1.1

on my local installation the Vary entry does not exist, so
maybe it depends on this, i don't know...

greetings,
MicFra