HTTP-Polling problems

Hello again,

after I've found out that there are no session key problems with HTTP-Polling and JSJaC as experienced with HTTP-Binding and JSJaC, I put my focus on a running JSJaC-client with HTTP-Polling. First I've tested MUCKl by myself with Opera, Firefox, IE6, IE7 and Safari. No problems (yes!).
But then i've invited some users. And again, weird things happened and users are unlucky again.

One example (I have dozens): one user just gets disconnected. I don't know why, ejabberd put this into its log:

[code]
=INFO REPORT==== 2008-04-07 18:40:14 ===
D(<0.499.0>:ejabberd_http:224) : (#Port<0.884>) http query: 'POST' /http-poll/

=INFO REPORT==== 2008-04-07 18:40:14 ===
D(<0.499.0>:ejabberd_http:338) : client data: "84463723116641361deea82ba8227e7fc156ca1a;Y+boeMIJ2ErqU0ancu4D7GFFXK4=
;aPxIHtVIdTJXYJZE33FddNFAASA=,"

=INFO REPORT==== 2008-04-07 18:40:14 ===
D(<0.499.0>:ejabberd_http:263) : ["http-poll"] matches ["http-poll"]

=INFO REPORT==== 2008-04-07 18:40:14 ===
D(<0.482.0>:ejabberd_receiver:297) : Received XML on stream = []

=INFO REPORT==== 2008-04-07 18:40:16 ===
I(<0.430.0>:ejabberd_c2s:1289) : ({socket_state,ejabberd_http_poll,{http_poll,<0.428.0>},<0.429.0>}) Close session for user@domain.de/ffddb7024f2bace26e8d7899a467d8a5779dc758
[/code]

(real jid has been replaced by user@domain.de)

No idea why ejabberd closes the session here. Some users still get just disconnected, others are kicked out of the room with the message "This participant is kicked from the room because he sent an error message to another participant: service-unavailable"

Seems to me that there are several things going wrong.. Any advice or idea? Thanks!

cheers,
flip