This bug was present in Ubuntu Gnome 16.04 LTS with GDM, but did a clean install of Ubutnu 16.04 LTS with Unity and LightDM, and the bug is still present.
How to reproduce:
1. Boot the system, wait for LightDM to start and show the Ubuntu Unity greeter.
2. Log in as a user.
3. From the power menu (top right), choose an other user
4. In the password-promt (greeter) for the user, type in the correct password
At this point, one of three thing might happen:
a- The desktop, desktop icons, Unity-launcher and main menu for the user is loaded. The user can use the system as expected!
b- The desktop, desktop icons and Unity-launcher the user is loaded. However, just before the main-menu-bar at the tops loads, the the graphics freezes. I can move the cursor, but that's it. It is not possible to click or do anything with the mouse-cursor.
c- Same as (b), but during this process the screen goes complete blank (black), with only the cursor showing (and moving).
When (b) or (c), pressing ALT+F1-F6 does not help, the screen just stays the same (except the cursor dispersers). Pressing ALT+F7 afterwards does not bring the cursor back.
The system has not frozen. I can SSH to the box and it lives as nothing has happened. It's only effecting the display/graphics.
This bug happens about 1/3 of the times I switch the user. Sometimes I can switch to and from users several times (2-5) before this bug comes to life.
ProblemType: Bug
DistroRelease: Ubuntu 16.04
Package: linux-image-4.4.0-57-generic 4.4.0-57.78
ProcVersionSignature: Ubuntu 4.4.0-57.78-generic 4.4.35
Uname: Linux 4.4.0-57-generic x86_64
ApportVersion: 2.20.1-0ubuntu2.4
Architecture: amd64
AudioDevicesInUse:
USER PID ACCESS COMMAND
/dev/snd/controlC0: sitron 1903 F.... pulseaudio
Date: Mon Dec 26 16:58:42 2016
HibernationDevice: RESUME=UUID=9d82d48a-107c-4d15-844d-c4ba62a3d320
InstallationDate: Installed on 2016-12-18 (8 days ago)
InstallationMedia: Ubuntu 16.04.1 LTS "Xenial Xerus" - Release amd64 (20160719)
IwConfig:
lo no wireless extensions.
eno1 no wireless extensions.
Lsusb:
Bus 002 Device 003: ID 046d:c52b Logitech, Inc. Unifying Receiver
Bus 002 Device 002: ID 8087:0024 Intel Corp. Integrated Rate Matching Hub
Bus 002 Device 001: ID 1d6b:0002 Linux Foundation 2.0 root hub
Bus 001 Device 002: ID 8087:0024 Intel Corp. Integrated Rate Matching Hub
Bus 001 Device 001: ID 1d6b:0002 Linux Foundation 2.0 root hub
ProcFB: 0 inteldrmfb
ProcKernelCmdLine: BOOT_IMAGE=/boot/vmlinuz-4.4.0-57-generic root=UUID=2a82deba-0eba-4358-b17c-65be40fe066f ro quiet splash vt.handoff=7
PulseList:
Error: command ['pacmd', 'list'] failed with exit code 1: Home directory not accessible: Permission denied
No PulseAudio daemon running, or not running as session daemon.
RelatedPackageVersions:
linux-restricted-modules-4.4.0-57-generic N/A
linux-backports-modules-4.4.0-57-generic N/A
linux-firmware 1.157.6
RfKill:
SourcePackage: linux
UpgradeStatus: No upgrade log present (probably fresh install)
dmi.bios.date: 10/21/2016
dmi.bios.vendor: Intel Corp.
dmi.bios.version: GKPPT10H.86A.0060.2016.1021.1324
dmi.board.name: DCP847SKE
dmi.board.vendor: Intel Corporation
dmi.board.version: G80890-105
dmi.chassis.type: 3
dmi.modalias: dmi:bvnIntelCorp.:bvrGKPPT10H.86A.0060.2016.1021.1324:bd10/21/2016:svn:pn:pvr:rvnIntelCorporation:rnDCP847SKE:rvrG80890-105:cvn:ct3:cvr:
This change was made by a bot.