Thanks, Both!
No mapped network drive because I have an aversion to them (Windows Explorer navigation performance to any folder is normally piss-poor if the mapped drive is unavailable for some reason).
I just tried the new shortcut idea but it didn't help, unfortunately. In fact, simply going to the Windows Explorer address bar and typing \\the.I.P.address followed by "return" results in the pop-up login dialogue the first time it is done since boot. Grrrr.
Anything to hack in the Windows Registry? (Yes, it is backed up)
Ta,
XV