This problem is new in Ubuntu 18.10; it did not occur with 18.04.
When my laptop, an HP EliteBook 9470m, with Intel Ivy Bridge graphics, comes out of resume, often the UI is unresponsive. Typically I get a black screen, a screen with just the GNOME top bar, or what the screen was showing before the laptop was suspended. The mouse cursor moves but the UI is unresponsive to input.
If I switch VTs with Ctrl+Alt+F1, the lock screen shows, I can enter my password and after that my GUI session begins to work again, where I left off.
The problem appears to increase in frequency when I add external monitors.
It occurs on every suspend/resume if one or more external monitors (DisplayPort or VGA) have been used since the laptop was booted, even if they were present at boot, or subsequently removed.
If an extra monitor was plugged in while the laptop was turned off (scenario: come home, put laptop in docking station with extra monitor attached, turn on) then often the UI will still fail to respond after switching to the lock screen with Ctrl+Alt+F1 and I will need to reboot the laptop.
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ProblemType: Bug
ApportVersion: 2.20.10-0ubuntu13.1
Architecture: amd64
CurrentDesktop: ubuntu:GNOME
DistroRelease: Ubuntu 18.10
InstallationDate: Installed on 2018-08-13 (191 days ago)
InstallationMedia: Ubuntu 18.04.1 LTS "Bionic Beaver" - Release amd64 (20180725)
Package: gnome-shell
PackageArchitecture: amd64
ProcVersionSignature: Ubuntu 4.18.0-15.16-generic 4.18.20
Tags: cosmic
Uname: Linux 4.18.0-15-generic x86_64
UpgradeStatus: Upgraded to cosmic on 2018-10-19 (124 days ago)
UserGroups: adm cdrom dip libvirt lpadmin plugdev sambashare sudo
_MarkForUpload: True
mtime.conffile..etc.gdm3.custom.conf: 2018-12-05T11:18:35.863354
The mouse cursor moving is handled by the Xorg process, so if nothing else is responding then that suggests the problem is entirely in gnome-shell.
To start, please run this command to send us more information about the machine:
apport-collect 1816896