[imp] IMP w IE6 locks via SSL at login (yes, I've read the FAQ)

[Vizitiu, Ciprian]

Horde 2.2.3. Apache 2.0.40. php 4.2.2. IE6 on XP Prof; Latest patches in
place.

Sorry for bringing this issue again but I'm really out ideas! If I use
https with the above config, IMP locks if accessed via IE6. The puzzling
thing is that in some cases it works! I can't tell why, apparently
without any reason at all. Useless to say, all other browsers can access
IMP without any problem.

Anybody with any hint/idea? :-o

relevant httpd.conf:

NameVirtualHost 192...:443
<VirtualHost 192...:443>
    ServerAdmin     webmaster at somesite.org
    ServerName      webmail.somesite.org
    SSLEngine                   on
    SSLProtocol                 All
    SSLCipherSuite
ALL:!ADH:!EXPORT56:RC4+RSA:+HIGH:+MEDIUM:+LOW:+SSLv2:+SSLv3:+EXP:+eNULL
    SSLCertificateFile
/usr/local/apache2/conf/ssl/crt/webmail.crt
    SSLCertificateKeyFile
/usr/local/apache2/conf/ssl/key/webmail.key
    DocumentRoot    /var/www/html
    ErrorLog      logs/webmail-error_log
    CustomLog       logs/webmail-acces_log common
    SetEnvIf                    User-Agent ".*MSIE.*" \
         nokeepalive ssl-unclean-shutdown \
         downgrade-1.0 force-response-1.0
    KeepAlive   Off
</VirtualHost>