The links in the content area are missing /CustomFields when you
navigate from the top menu in Configuration > Global > Custom Fields.
The top menu final link is ok just the ones in the content area.
This appears to be a session variable issue, it only happens when you
navigate through the top menu and try to click one of the final links
(users, groups, queues, tickets, ticket transactions) in the main
window. If you navigate through the main window it appears to be ok.
I believe I have posted something similar this before but it appears to
only happen in the situation described above, perhaps as a result of the
fix (which was top menu links not working).