Screen "blanks" even with valid video signal after Desktop is left on for an extended period

[Axil Therian]

Video on my monitor will go "blank", or to essentially a backlit black screen, after the desktop is left on for several hours.

NOTE: this is not my computer Hibernating. When i'm actively using the computer, the screen will blank for roughly 1-2 second then return to normal,. progressively getting longer over time until i have to reboot the machine.

i've tested this nunder:

x3 Different Montiors: All the same issue.

Linux Mint 16 on /dev/sdb0: Video Worked fine.

Windows 10 Home on /dev/sdb1: Video Worked fine

this also occurs, sometimes when videos are being streamed in firefox

lsb_release:

Description: Ubuntu 15.04
Release: 15.04

XORG Release:

xorg:
  Installed: 1:7.7+7ubuntu4
  Candidate: 1:7.7+7ubuntu4
  Version table:
 *** 1:7.7+7ubuntu4 0
        500 http://us.archive.ubuntu.com/ubuntu/ vivid/main amd64 Packages
        100 /var/lib/dpkg/status

ProblemType: Bug
DistroRelease: Ubuntu 15.04
Package: xorg 1:7.7+7ubuntu4
ProcVersionSignature: Ubuntu 3.19.0-25.26-generic 3.19.8-ckt2
Uname: Linux 3.19.0-25-generic x86_64
.tmp.unity.support.test.0:

ApportVersion: 2.17.2-0ubuntu1.2
Architecture: amd64
CompizPlugins: No value set for `/apps/compiz-1/general/screen0/options/active_plugins'
CompositorRunning: compiz
CompositorUnredirectDriverBlacklist: '(nouveau|Intel).*Mesa 8.0'
CompositorUnredirectFSW: true
CurrentDesktop: Unity
Date: Thu Aug 13 15:54:45 2015
DistUpgraded: Fresh install
DistroCodename: vivid
DistroVariant: ubuntu
DkmsStatus:
 virtualbox, 4.3.26, 3.19.0-15-generic, x86_64: installed
 virtualbox, 4.3.26, 3.19.0-25-generic, x86_64: installed
ExtraDebuggingInterest: Yes
GraphicsCard:
 Advanced Micro Devices, Inc. [AMD/ATI] Juniper XT [Radeon HD 5770] [1002:68b8] (prog-if 00 [VGA controller])
   Subsystem: Advanced Micro Devices, Inc. [AMD/ATI] Device [1002:2543]
InstallationDate: Installed on 2015-08-03 (10 days ago)
InstallationMedia: Ubuntu 15.04 "Vivid Vervet" - Release amd64 (20150422)
MachineType: Gateway FX6840
ProcKernelCmdLine: BOOT_IMAGE=/boot/vmlinuz-3.19.0-25-generic root=UUID=e03166ec-57f3-41ff-a3ba-33d1ef3afedf ro quiet splash crashkernel=384M-:128M vt.handoff=7
SourcePackage: xorg
Symptom: display
UdevLog: Error: [Errno 2] No such file or directory: '/var/log/udev'
UpgradeStatus: No upgrade log present (probably fresh install)
dmi.bios.date: 05/17/2010
dmi.bios.vendor: American Megatrends Inc.
dmi.bios.version: P01-A3
dmi.board.asset.tag: To Be Filled By O.E.M.
dmi.board.name: FX6840
dmi.board.vendor: Gateway
dmi.chassis.type: 3
dmi.chassis.vendor: Gateway
dmi.modalias: dmi:bvnAmericanMegatrendsInc.:bvrP01-A3:bd05/17/2010:svnGateway:pnFX6840:pvr:rvnGateway:rnFX6840:rvr:cvnGateway:ct3:cvr:
dmi.product.name: FX6840
dmi.sys.vendor: Gateway
version.compiz: compiz 1:0.9.12.1+15.04.20150410.1-0ubuntu1
version.ia32-libs: ia32-libs N/A
version.libdrm2: libdrm2 2.4.60-2
version.libgl1-mesa-dri: libgl1-mesa-dri 10.5.2-0ubuntu1
version.libgl1-mesa-dri-experimental: libgl1-mesa-dri-experimental N/A
version.libgl1-mesa-glx: libgl1-mesa-glx 10.5.2-0ubuntu1
version.xserver-xorg-core: xserver-xorg-core 2:1.17.1-0ubuntu3
version.xserver-xorg-input-evdev: xserver-xorg-input-evdev 1:2.9.0-1ubuntu2
version.xserver-xorg-video-ati: xserver-xorg-video-ati 1:7.5.0-1ubuntu2
version.xserver-xorg-video-intel: xserver-xorg-video-intel 2:2.99.917-1~exp1ubuntu2.2
version.xserver-xorg-video-nouveau: xserver-xorg-video-nouveau 1:1.0.11-1ubuntu2build1
xserver.bootTime: Thu Aug 13 14:34:27 2015
xserver.configfile: default
xserver.devices:
 input Power Button KEYBOARD, id 6
 input Power Button KEYBOARD, id 7
 input Logitech USB Receiver MOUSE, id 8
 input Logitech USB Receiver KEYBOARD, id 9
 input AT Translated Set 2 keyboard KEYBOARD, id 10
xserver.errors:

xserver.logfile: /var/log/Xorg.0.log
xserver.version: 2:1.17.1-0ubuntu3
xserver.video_driver: radeon

[penalvch (penalvch)]

Axil Therian, thank you for reporting this and helping make Ubuntu better. To see if this is already fixed, could you please test for this via http://cdimage.ubuntu.com/daily-live/current/ and advise to the results?

[Launchpad Janitor (janitor)]

[Expired for xorg (Ubuntu) because there has been no activity for 60 days.]