To have Watchtower Library ( & Office 2016 ) run without issues on computers 3. & 4. I just do steps A thru D
A - Run msconfig
B - System Configuration – General – Select “Selective startup” ( “Load startup items” is checked )
C - System Configuration – Services – Check “Hide all Microsoft services” – Click on “Disable all” – Click on “OK”
D -. Restart computer – ( In my situation Watchtower Library ( & Office 2016 ) now run without issues )