User Level Access Control -- Win 98 & XP

I have a small network consisting of three machines and a Linksys Router.
Two Machines, a Dell Dimension and Dell Latitude are running Win98 SE and
the Third, a Carillon is running XP Pro. All Three machines are present in
Network Neighborhood on each machine and can access each other, to the point
of the top level directory at least, thru the neighborhood. User Level
Access Control is implemented on all the machines and all three supposedly
obtain the list of authorized users from the Carillon running XP. The
Dimension and Carillon can communicate with no problem, sharing resources
etc. However, the Latitude is another story. Though it appears in Network
Neighborhood on the other two machines, neither can access its resources
because the Latitude will not retrieve the list of authorized users.
Whenever the attempt to add authorized users to any share on the Latitude is
made, I get the error message "You Cannot view the list of users at this
time. Please try later." MS Knowledge base does have an article dealing with
that error, but it is of no help. From my reading I have about concluded
that the problem has something to do with MAPI but I can neither find a
workaround nor a resolution. As well, when I try to map a drive on one of
the other computers to the Latitude, I get a message to the effect the share
cannot be found. I have gone so far as to reinstall windows on the Latitude,
but no change.
If any of you have any idea as to what I can do to make things work, I would
certainly appreciate hearing from you.
Thank You
_DAVID R. WARNER, JR.