[squid-users] Problem with unparseable HTTP header field

When I surf to http://www.abstractserver.de/da2005/avi/e/Abs_revi.htm
and enter any number/character and click "Submit my query", I get an
error page ("Invalid Response" The HTTP Response message received from
the contacted server could not be understood or was otherwise
malformed. Please contact the site operator. Your cache administrator
may be able to provide you with more details about the exact nature of
the problem if needed. ) and in my cache.log:

-- snip ---
2005/02/18 14:42:23| ctx: exit level 0
2005/02/18 14:42:23| ctx: enter level 0: 'http://www.abstractserver.de/bin46/da2005/avi/e/avicgi.exe'
2005/02/18 14:42:23| WARNING: unparseable HTTP header field near {HTTP/1.1 200 OK
content-type: text/html
content-length: 2205
Connection: Keep-Alive
}
-- snip ---

with squid/2.5.STABLE7 (Debian/testing)

How can I work around this?
Without a proxy I can access the site OK (I can, my users MUST use the
proxy).

-- 
Ralf Hildebrandt (i.A. des IT-Zentrum)          Ralf.Hildebrandt@charite.de
Charite - Universitätsmedizin Berlin            Tel.  +49 (0)30-450 570-155
Gemeinsame Einrichtung von FU- und HU-Berlin    Fax.  +49 (0)30-450 570-962
IT-Zentrum Standort CBF                 send no mail to spamtrap@charite.de