Clients can't see group members in Distribution List

Hi,

The situation is as follow:
All users can see group members in AD but when trying to
see the members group from the Distribution List
(Outlook), they can't see the group members

There's is no problem sending mail to those groups

I did change domain policy a few day's ago requiring
users to change password every 60 days and maintaining
password complexity, I don't think this is related but
this is a need to know.

Thanks