Display freezes/unresponsive after locking screen for a while

[Rafael]

Everyday, I lock the screen when I'm away from the computer and, everyday, if I am more than two hours away, the bloody computer freezes its graphical interface: not the laptop itself, still running, but to no avail.

Workaround - Emergency Sync + Emergency Umount + Reboot with the laptop keyboard, as the external mouse and keyboard and the monitors are unresponsive. The machine is connected and could be accessed via ssh, if I had another computer at home.

1) Release:

$ lsb_release -rd
Description: Ubuntu 17.04
Release: 17.04

2) Version
$ apt-cache policy xorg
xorg:
  Installed: 1:7.7+16ubuntu3
  Candidate: 1:7.7+16ubuntu3
  Version table:
 *** 1:7.7+16ubuntu3 500
        500 http://br.archive.ubuntu.com/ubuntu zesty/main amd64 Packages
        100 /var/lib/dpkg/status

-- Rafael

ProblemType: Bug
DistroRelease: Ubuntu 17.04
Package: xorg 1:7.7+16ubuntu3
ProcVersionSignature: Ubuntu 4.10.0-35.39-generic 4.10.17
Uname: Linux 4.10.0-35-generic x86_64
.tmp.unity_support_test.0:

ApportVersion: 2.20.4-0ubuntu4.5
Architecture: amd64
CompizPlugins: No value set for `/apps/compiz-1/general/screen0/options/active_plugins'
CompositorRunning: None
Date: Sun Oct 1 08:25:16 2017
DistUpgraded: Fresh install
DistroCodename: zesty
DistroVariant: ubuntu
DpkgLog:

ExtraDebuggingInterest: Yes
GraphicsCard:
 Intel Corporation HD Graphics 520 [8086:1916] (rev 07) (prog-if 00 [VGA controller])
   Subsystem: Acer Incorporated [ALI] HD Graphics 520 [1025:100c]
InstallationDate: Installed on 2017-04-16 (167 days ago)
InstallationMedia: Ubuntu 16.04.1 LTS "Xenial Xerus" - Release amd64 (20160719)
MachineType: Acer Aspire E5-574G
ProcKernelCmdLine: BOOT_IMAGE=/boot/vmlinuz-4.10.0-35-generic root=UUID=4d4e9fdd-82f0-489b-8cee-66717d903185 ro nouveau.modeset=0 splash quiet
Renderer: Software
SourcePackage: xorg
UpgradeStatus: No upgrade log present (probably fresh install)
dmi.bios.date: 03/04/2016
dmi.bios.vendor: Insyde Corp.
dmi.bios.version: V1.14
dmi.board.asset.tag: Type2 - Board Asset Tag
dmi.board.name: Zoro_SL
dmi.board.vendor: Acer
dmi.board.version: V1.14
dmi.chassis.type: 10
dmi.chassis.vendor: Chassis Manufacturer
dmi.chassis.version: Chassis Version
dmi.modalias: dmi:bvnInsydeCorp.:bvrV1.14:bd03/04/2016:svnAcer:pnAspireE5-574G:pvrV1.14:rvnAcer:rnZoro_SL:rvrV1.14:cvnChassisManufacturer:ct10:cvrChassisVersion:
dmi.product.name: Aspire E5-574G
dmi.product.version: V1.14
dmi.sys.vendor: Acer
version.compiz: compiz 1:0.9.13.1+17.04.20170109-0ubuntu1
version.ia32-libs: ia32-libs N/A
version.libdrm2: libdrm2 2.4.76-1
version.libgl1-mesa-dri: libgl1-mesa-dri 17.0.7-0ubuntu0.17.04.1
version.libgl1-mesa-dri-experimental: libgl1-mesa-dri-experimental N/A
version.libgl1-mesa-glx: libgl1-mesa-glx 17.0.7-0ubuntu0.17.04.1
version.xserver-xorg-core: xserver-xorg-core 2:1.19.3-1ubuntu1.1
version.xserver-xorg-input-evdev: xserver-xorg-input-evdev N/A
version.xserver-xorg-video-ati: xserver-xorg-video-ati 1:7.9.0-0ubuntu1
version.xserver-xorg-video-intel: xserver-xorg-video-intel 2:2.99.917+git20170309-0ubuntu1
version.xserver-xorg-video-nouveau: xserver-xorg-video-nouveau 1:1.0.14-0ubuntu1
xserver.bootTime: Thu Aug 31 18:00:16 2017
xserver.configfile: default
xserver.devices: input ETPS/2 Elantech Touchpad TOUCHPAD, id 6
xserver.errors:
 Failed to load module "nvidia" (module does not exist, 0)
 Failed to load module "nvidia" (module does not exist, 0)
 [drm] Failed to open DRM device for (null): -22
 Screen 0 deleted because of no matching config section.
 AIGLX: reverting to software rendering
xserver.logfile: /var/log/Xorg.0.log
xserver.outputs:

xserver.version: 2:1.19.3-1ubuntu1.1

[dino99 (9d9)]

That version is now dead
http://news.softpedia.com/news/ubuntu-17-04-zesty-zapus-has-reached-end-of-life-upgrade-to-ubuntu-17-10-now-519360.shtml