Black wallpaper instead than set image

[Andrea Bonarini]

The image set as wallpaper appears for one second and then is replaced by a black screen.
This occurs after a hard reset. After a suspension: nothing worked and I had to do a hard reset by switching the machine off. At restart I'm in the mentioned situation and the usual methods to reset the wall paper do not fix the problem.
Thank you!

ProblemType: Bug
DistroRelease: Ubuntu 20.04
Package: xorg 1:7.7+19ubuntu14
ProcVersionSignature: Ubuntu 5.4.0-70.78-generic 5.4.94
Uname: Linux 5.4.0-70-generic x86_64
.tmp.unity_support_test.0:

ApportVersion: 2.20.11-0ubuntu27.16
Architecture: amd64
BootLog:

CasperMD5CheckResult: skip
CompizPlugins: No value set for `/apps/compiz-1/general/screen0/options/active_plugins'
CompositorRunning: compiz
CompositorUnredirectDriverBlacklist: '(nouveau|Intel).*Mesa 8.0'
CompositorUnredirectFSW: true
Date: Sun Mar 28 13:23:15 2021
DistUpgraded: Fresh install
DistroCodename: focal
DistroVariant: ubuntu
ExtraDebuggingInterest: Yes, if not too technical
GraphicsCard:
 Intel Corporation HD Graphics 620 [8086:5916] (rev 02) (prog-if 00 [VGA controller])
   Subsystem: Dell HD Graphics 620 [1028:07a7]
InstallationDate: Installed on 2017-06-16 (1381 days ago)
InstallationMedia: Ubuntu 16.04.2 LTS "Xenial Xerus" - Release amd64 (20170215.2)
Lsusb:
 Bus 002 Device 001: ID 1d6b:0003 Linux Foundation 3.0 root hub
 Bus 001 Device 003: ID 1bcf:2b96 Sunplus Innovation Technology Inc. Integrated_Webcam_HD
 Bus 001 Device 002: ID 093a:2510 Pixart Imaging, Inc. Optical Mouse
 Bus 001 Device 005: ID 0a5c:5832 Broadcom Corp. 5880
 Bus 001 Device 001: ID 1d6b:0002 Linux Foundation 2.0 root hub
MachineType: Dell Inc. Latitude 5480
ProcKernelCmdLine: BOOT_IMAGE=/boot/vmlinuz-5.4.0-70-generic root=UUID=0db16900-e9f1-49a7-b5db-508d231aac23 ro drm.debug=0xe plymouth:debug
SourcePackage: xorg
UpgradeStatus: No upgrade log present (probably fresh install)
dmi.bios.date: 01/07/2020
dmi.bios.vendor: Dell Inc.
dmi.bios.version: 1.17.1
dmi.board.name: 0NDFXD
dmi.board.vendor: Dell Inc.
dmi.board.version: A00
dmi.chassis.type: 10
dmi.chassis.vendor: Dell Inc.
dmi.modalias: dmi:bvnDellInc.:bvr1.17.1:bd01/07/2020:svnDellInc.:pnLatitude5480:pvr:rvnDellInc.:rn0NDFXD:rvrA00:cvnDellInc.:ct10:cvr:
dmi.product.family: Latitude
dmi.product.name: Latitude 5480
dmi.product.sku: 07A7
dmi.sys.vendor: Dell Inc.
version.compiz: compiz 1:0.9.14.1+20.04.20200211-0ubuntu1
version.libdrm2: libdrm2 2.4.102-1ubuntu1~20.04.1
version.libgl1-mesa-dri: libgl1-mesa-dri 20.2.6-0ubuntu0.20.04.1
version.libgl1-mesa-glx: libgl1-mesa-glx 20.2.6-0ubuntu0.20.04.1
version.xserver-xorg-core: xserver-xorg-core 2:1.20.9-2ubuntu1.2~20.04.1
version.xserver-xorg-input-evdev: xserver-xorg-input-evdev 1:2.10.6-1
version.xserver-xorg-video-ati: xserver-xorg-video-ati 1:19.1.0-1
version.xserver-xorg-video-intel: xserver-xorg-video-intel 2:2.99.917+git20200226-1
version.xserver-xorg-video-nouveau: xserver-xorg-video-nouveau 1:1.0.16-1