Ok, this has been a LONG standing issue for me and since I have a
workaround in place its not a major issue thankfully.

But... - Heres whats going on:

If one of my clients does not have NMAS Authentication turned to Off its
like its a virtual timebomb waiting to go off (well, for the end user
anyway, nothing actually serious happens..) - Essentially, the client will
be unable to see ANY trees and therefore, unable to log in at all.

I've asked about this over at the 6.x administration support forum, the
history on that can be found here:

As always, any/all tips, hints suggestions greatly appreciated!