Contact that used to work now doesn't

I have a contact in my messenger that used to both show as active when online
and allow me to send an offline message when offline for later delivery. But
now the contact neither appears as online nor can I send an offline message
-- I'm only allowed to E-Mail. Nothing on my machine has changed relative to
instant messaging except I upgrading my browser version of msn mail to the
latest version. This same contact has a hotmail address that is entered as
the contact linkage.

Oddly, it does not work to click Add This Person to Contacts when the
contact IMs me (who he can see online using Windows Live Messenger just
fine). The link simply does not react. Nothing happens. Any ideas of what
is going on?