May be due to edit of /etc/systemd/login.conf edited to suspend computer if login screen is up. uncommented:
#IdleAction=suspend
#IdleActionSec=15min
and saw the behavior.
re-commented and have not seen the behavior. This edit has worked to suspend the gdm login screen since 12.04 to 15.04. It does not work for 15.10 or 16.04
~$ cat /etc/systemd/logind.conf
# This file is part of systemd.
#
# systemd is free software; you can redistribute it and/or modify it
# under the terms of the GNU Lesser General Public License as published by
# the Free Software Foundation; either version 2.1 of the License, or
# (at your option) any later version.
#
# Entries in this file show the compile time defaults.
# You can change settings by editing this file.
# Defaults can be restored by simply deleting this file.
#
# See logind.conf(5) for details.
May be due to edit of /etc/systemd/ login.conf edited to suspend computer if login screen is up. uncommented:
#IdleAction=suspend 15min
#IdleActionSec=
and saw the behavior.
re-commented and have not seen the behavior. This edit has worked to suspend the gdm login screen since 12.04 to 15.04. It does not work for 15.10 or 16.04
~$ cat /etc/systemd/ logind. conf
# This file is part of systemd.
#
# systemd is free software; you can redistribute it and/or modify it
# under the terms of the GNU Lesser General Public License as published by
# the Free Software Foundation; either version 2.1 of the License, or
# (at your option) any later version.
#
# Entries in this file show the compile time defaults.
# You can change settings by editing this file.
# Defaults can be restored by simply deleting this file.
#
# See logind.conf(5) for details.
[Login] ses=no rs=root xSec=5 =poweroff ey=suspend eKey=hibernate h=suspend hDocked= ignore Inhibited= no reInhibited= no noreInhibited= no eInhibited= yes Sec=30s 15min rySize= 10%
#NAutoVTs=6
#ReserveVT=6
#KillUserProces
#KillOnlyUsers=
#KillExcludeUse
#InhibitDelayMa
#HandlePowerKey
#HandleSuspendK
#HandleHibernat
#HandleLidSwitc
#HandleLidSwitc
#PowerKeyIgnore
#SuspendKeyIgno
#HibernateKeyIg
#LidSwitchIgnor
#HoldoffTimeout
#IdleAction=suspend
#IdleActionSec=
#RuntimeDirecto
#RemoveIPC=yes
#UserTasksMax=12288