Mark,
Thank you so much!!
Your Input is still serving superbly in March 15, 2019. So simple yet so obscure!!
I installed version 1803 after updating a pc from an earlier version of Windows 10 just a number of days ago. This issue was driving me round the twist for a couple of days as I could not network to the PC whatsoever. I would go through the process so many experienced here on the forum by disabling the PIN through the settings options. But it would come back to hinder on re-login.
The surprising thing is I have two other PC's all on 1803 since last year and never encountered this issue. It must have been a blissful fluke twice!
Microsoft has an uncanny habit of fixing things that don't need to be fixed. To hide the solution under a "sign-in options" dialogue is basically a design of what I call "crippling flexibility".
Thanks again, problem solved.
Cheers
Daniel