Emails flagged (different colors) in shared mailbox in Outlook 2010 not visible to Outlook 2003 users

We are a group of users accessing a shared mailbox. The supervisor has been migrated to Outlook 2010 and the rest of the group is still using Outlook 2003.

• When the supervisor flags a color of an email in the shared mailbox, the users running 2003 are unable to see the change.

• The supervisor (running 2010) can see changes that are flagged by the 2003 users.

Help!