Yippee ....
but...
So I realised, that when I was installing the contrib nodes on the alternate install, they'd be the lastest versions
So I went back to my orig instance and started going thru the palette and updating them - unfortunately I did a few a t a time in between testing, so I don't know which actual one was causing it!
But, since whatever bug was in one of them has been fixed, I think it's OK to put this one to bed now
Thanks for all the help/suggestions as to fixing it!