I've solved the problem. It has to do with using either Wayland versus Xorg. I search
for Gnome bugs relating to logging in and found one that said to edit
/etc/gdm/custom.conf. From the script fragment below, uncomment the line below to force
the login screen to use Xorg, save and reboot
[daemon]
# Uncoment the line below to force the login screen to use Xorg
#WaylandEnable=false
# JEH
WaylandEnable=false
Apparently Wayland does not currently work on an HP Pavilion notebook.
It is good that one can select between Wayland and Xorg.
Consider this thread closed.