sspi + SSL + valid-user not working

Hi everybody, I am trying getting to work together Apache 2.0.59 with
OpenSSL and mod_auth_sspi 1.0.4 . I am very close to what I need - that
is protecting an area of my web site with SSL and Windows domain
authentication to give access to all the domain users - but here is
what happens.

1) if I activate SSL, everything works with Firefox, but IE gives me a
"Cannot find server or DNS Error" (???); the two browser have the same
connection configuration

2) if I disable SSL, everything works fine on both browsers (but my
passwords are not safe!)

3) if I activate SSL and disable the "Require valid-user" directive,
everything works fine on both browsers (but everyone has access!)

<Location /test>
AuthName "Authentication"
AuthAuthoritative On
SSLRequireSSL

AuthType SSPI
SSPIAuth On
SSPIAuthoritative Off
SSPIDomain MYDOMAINNAME
SSPIOfferBasic Off

Require valid-user
</Location>

Any advice?

Giacecco