Further to my earlier comment, - I can now report that I can also create frozen fish, at will, on my system!
..... Full details given here....
https://www.feldoncentral.com/forums...ead.php?t=4388
This is the thread, started by Tiny, that first reported the
'Frozen fish in a window'. - You will notice that those reporting the same problem were also all using more than one screen.