[xubuntu-users] Desktop settings no longer work (16.04.5)

[MR ZenWiz]

As of a week or two ago, my home desktop doesn't respond to any
Desktop settings at all.  the background is a weave of blue gray and
the mouse right click no longer functions to bring up the desktop
menu.

Anyone else seeing this?  I'm running:

4.10.0-32-generic #36~16.04.1-Ubuntu SMP Wed Aug 9 09:19:02 UTC 2017
x86_64 GNU/Linux
DISTRIB_ID=Ubuntu
DISTRIB_RELEASE=16.04
DISTRIB_CODENAME=xenial
DISTRIB_DESCRIPTION="Ubuntu 16.04.5 LTS"

M/B:    ASRock Z97 Pro4
f/w:    AMI BIOS P2.20 5/12/2015
CPU:    Intel i7-4790K 4GHz
ram:    16GB EVGA DDR3 2400MHz (PC3-19200) 2x8G
K/b:    Dell DP/N 0U4730 USB PID LZ03778D0AFH
Mou:    Logitech MX3000 Cordless Desktop (laser mouse)
vid:    on-board (Xeon E3 1200 v3, i915 driver)

Any suggestions welcome.

MR