Relatively new 16.04 installation after some recent updates no longer shutsdown, instead it logs out. What is worse when I log back in, networking is dead.
Google finds the problem when using "Plank" I believe this is the Mac like bar on the bottom which I despise (even when I used a Mac) and have never used. Is some stub of it running by default?
To only way to get back is to kill the power, may not be too bad since it is logged out, but ...
Any solution?
I wouldn't force power it off, instead go to the terminal and type "sudo shutdown now" to shut it off, to shutdown and restart it the same command works with " -r" added at the end, but as far as the actual problem I'm on 18.04 so i wouldn't know
First thing I tried didn't work. I get a message:
"Failed to start poweroff.target: Transaction is destructive"
See system logs and 'systemctrl status poweroff.target' for details.
Perhaps I'm starting to understand why the switch to systemd was so controversial 
Its sems to be some kind of weird interaction with using an external hdmi monitor on this ASUS FX-705GM Notebook.
But there is no choice but to kill the power once it happens as the network doesn't work after login from the failed shutdown.
try in a terminal
sudo poweroff
Don't work. The damn thing is in a logout/log in loop.
I'm unbelievably PO'd at the moment. This is the kind of crap that made me leave Windows!!!
Had to pull the plug after installing the most recent updates that required a reboot. Seems every frigging update is needing a reboot now.
If I believed in conspiracy theories I might think this was Microsoft and Ubuntu getting in bed for WSL "Linux on Windows".
Sorry, I had to vent.
I tend to feel your pain wally333. Please check this page to see if their suggestions work for you.
Edit: a bug report on this that might be worth reading - https://bugs.launchpad.net/ubuntu/+source/linux/+bug/1594023
None of this helps, much is too invasive to try.
The issue seems related to multimonitor. Its an ASUS FX705gm with Nvidia graphics and integrated Intel graphics.
I have a 4K monitor plugged into the external HDMI port. Its setup with the NVidia X Server Settings tool.
But the Ubuntu-Mate Display control panel is also active and required to make the 4K display be "primary" The builtin laptop LCD can be active or not. It seems to run on the Integrated graphics if the 4K display is attached.
Normally I have the LCD disabled and run with the lid closed. It doesn't matter if the LCD is active or not I get stuck in the login loop when I try to reboot.
What I tried after today's reboot required updates was to open the laptop lid, unplug the hdmi monitor, which forced the display back to the laptop LCD and reactivated it, aparently using the NVidia driver. Reboot from there worked normally. Plugging in the external monitor again at the bios screen had it boot back to the 4K display as primary with the LCD disabled.
PITA, but better than pulling the plug to reboot! I hooked up and old "passive" hdmi switch to avoid wear and tear on the laptop hdmi port.
What about killing dead/unresponsive processes?
Not sure what this refers to. I don't have any dead or unresponsive processes when I try to shut down.
I've apparently found a workaround.