Question : ISA, Single sign-on OWA2010 OWA2003 coexistence

Hi.

We are deploying Exchange 2010, and now we have OWA 2010 and 2003 in coexistence.
OWA 2010 and OWA 2003 are published with ISA Server 2006, with the same listener, but with separate certificates. (2 certificates on the same listener)
The listener is configured with Single sign-on (SSO) for the common domain (.dmmh.no) for OWA 2010 (mail.dmmh.no) and OWA 2003 (legacy.dmmh.no).

We use ISA Form Based Authentication for both OWA 2010 and OWA 2003.
OWA 2003 users still have to log on twice (first OWA 2010 and then OWA 2003)

Why isn't SSO working?

Answer : ISA, Single sign-on OWA2010 OWA2003 coexistence

Forgot to mention that I think the main problem was that the first site I logged in to (OWA2010) was defined as Local Intranet in IE, while the second site (OWA2003) was not defined as local Intranet in IE.
After removing the first site from the Local Intranet list in IE, SSO worked fine.