Screen locking issue

[rdlong]

I started installation of new software (Sound Juicer). I went away from my computer (before the screen asking for PW to install new software appeared) for more than 30 minutes, and the computer suspended.
I touched the keyboard to bring it out of suspend.
It went into a strange state. The password dialog was visble. When I entered my password, it brought up the task bar, but no windows. I could click on tasks, see the names of windows if there were multiple ones open (like OpenOffice), close tasks, and start them,but nothing would show a window.
I tried cancel, relogging in as myself, was finally forced to reboot.

ProblemType: Bug
DistroRelease: Ubuntu 18.04
Package: gnome-screensaver 3.6.1-8ubuntu3
ProcVersionSignature: Ubuntu 4.15.0-45.48-generic 4.15.18
Uname: Linux 4.15.0-45-generic x86_64
ApportVersion: 2.20.9-0ubuntu7.5
Architecture: amd64
CurrentDesktop: ubuntu:GNOME
Date: Sun Mar 3 21:29:02 2019
InstallationDate: Installed on 2018-06-21 (255 days ago)
InstallationMedia: Ubuntu 16.04.4 LTS "Xenial Xerus" - Release amd64 (20180228)
ProcEnviron:
 PATH=(custom, no user)
 XDG_RUNTIME_DIR=<set>
 LANG=en_US.UTF-8
 SHELL=/bin/bash
SourcePackage: gnome-screensaver
Symptom: security
Title: Screen locking issue
UpgradeStatus: Upgraded to bionic on 2018-11-18 (105 days ago)