Comment 0 for bug 1784473

After a fresh install of ubuntu 18.04LTS(dual booted with windows 7) when I selected ubuntu from the grub menu to boot into the OS. But I got a black screen I waited for few seconds but I was still at black screen. So, I forced shutdown the laptop. Again in second attempt to login I got black screen this time I waited for more than a minute and pressed power button once which suspended the pc then I pressed enter and I was presented with login screen. To solve the problem I followed this guide

and changed quiet splash to nomodeset quiet splash. After applying this fix there was no black screen at the time of login, but the laptop started to freeze randomly even when left idle for more than 30 mins it would freeze. I had force shutdown each time and this happened very frequently.
I again changed nomodeset quiet splash to quiet splash, which again leads to black screen after selecting ubuntu from the grub menu. I also did RAM test using Memtest86 from GRUB and everything was fine

systemd-analyze time
Startup finished in 6.015s (kernel) + 1min 26.820s (userspace) = 1min 32.836s reached after 1min 25.472s in userspace

ProblemType: Bug
DistroRelease: Ubuntu 18.04
Package: xorg 1:7.7+19ubuntu7
ProcVersionSignature: Ubuntu 4.15.0-29.31-generic 4.15.18
Uname: Linux 4.15.0-29-generic x86_64
ApportVersion: 2.20.9-0ubuntu7.2
Architecture: amd64
BootLog: Error: [Errno 13] Permission denied: '/var/log/boot.log'
CompositorRunning: None
CurrentDesktop: ubuntu:GNOME
Date: Tue Jul 31 00:17:48 2018
DistUpgraded: Fresh install
DistroCodename: bionic
DistroVariant: ubuntu
DkmsStatus: virtualbox, 5.2.10, 4.15.0-29-generic, x86_64: installed
ExtraDebuggingInterest: Yes
GpuHangFrequency: Several times a day
GpuHangReproducibility: Seems to happen randomly
GpuHangStarted: Immediately after installing this version of Ubuntu
 Advanced Micro Devices, Inc. [AMD/ATI] Sumo [Radeon HD 6480G] [1002:9648] (prog-if 00 [VGA controller])
   Subsystem: Hewlett-Packard Company Sumo [Radeon HD 6480G] [103c:3564]
InstallationDate: Installed on 2018-07-26 (4 days ago)
InstallationMedia: Ubuntu 18.04 LTS "Bionic Beaver" - Release amd64 (20180426)
MachineType: Hewlett-Packard HP Pavilion g4 Notebook PC
 PATH=(custom, no user)
ProcKernelCmdLine: BOOT_IMAGE=/boot/vmlinuz-4.15.0-29-generic root=UUID=007c6619-ca84-4c0f-8b16-7fa740dc0c3e ro quiet splash vt.handoff=1
SourcePackage: xorg
Symptom: display
Title: Xorg freeze
UpgradeStatus: No upgrade log present (probably fresh install) 01/24/2014
dmi.bios.vendor: Insyde
dmi.bios.version: F.6D
dmi.board.asset.tag: Base Board Asset Tag 3564
dmi.board.vendor: Hewlett-Packard
dmi.board.version: 21.47
dmi.chassis.type: 10
dmi.chassis.vendor: Hewlett-Packard
dmi.chassis.version: Chassis Version
dmi.modalias: dmi:bvnInsyde:bvrF.6D:bd01/24/2014:svnHewlett-Packard:pnHPPaviliong4NotebookPC:pvr0691130000204610000610100:rvnHewlett-Packard:rn3564:rvr21.47:cvnHewlett-Packard:ct10:cvrChassisVersion: 103C_5335KV G=N L=CON B=HP S=PAV HP Pavilion g4 Notebook PC
dmi.product.version: 0691130000204610000610100
dmi.sys.vendor: Hewlett-Packard
version.compiz: compiz N/A
version.libdrm2: libdrm2 2.4.91-2
version.libgl1-mesa-dri: libgl1-mesa-dri 18.0.5-0ubuntu0~18.04.1
version.libgl1-mesa-glx: libgl1-mesa-glx 18.0.5-0ubuntu0~18.04.1
version.xserver-xorg-core: xserver-xorg-core 2:1.19.6-1ubuntu4
version.xserver-xorg-input-evdev: xserver-xorg-input-evdev N/A
version.xserver-xorg-video-ati: xserver-xorg-video-ati 1:18.0.1-1
version.xserver-xorg-video-intel: xserver-xorg-video-intel 2:2.99.917+git20171229-1
version.xserver-xorg-video-nouveau: xserver-xorg-video-nouveau 1:1.0.15-2