In ConsloleOne (running on NW65sp6, eDir ver If I select (with
a right-click) a user and choose "Remote Manage", I get a message that
says the User Is not logged in to any workstation (error 1759).

That's a lie.

When I examine that User ID's properties, under the ZenWorks tab, under
"Logged in Workstation", I see the name of the PC on which that person in
logged in.

If I select to view the Details of that workstation, from there I am
able to Remote Control the PC and I find that very User ID logged in on
that workstation.

What's going on? Any clues?