sudo crashed with signal 5 in kill()

[Campbell Boyd]

I select Shutdown from the dropdown menu.
Desktop goes black then system error message appears.
After the error reporting, it sits there, nothing happening.
I select Shutdown from the dropdown menu. Nothing happens
I press the the power button - that is a quick press, not a long one.
The Ubuntu row of dots appear and it then seems to shut down normally.
No apparent problems on re-booting.

There was a terminal window open but it was sitting at the command prompt with nothing running.

ProblemType: Crash
DistroRelease: Ubuntu 16.04
Package: sudo 1.8.16-0ubuntu1.1
ProcVersionSignature: Ubuntu 4.4.0-34.53-generic 4.4.15
Uname: Linux 4.4.0-34-generic x86_64
ApportVersion: 2.20.1-0ubuntu2.1
Architecture: amd64
CurrentDesktop: Unity
Date: Fri Aug 19 23:47:02 2016
ExecutablePath: /usr/bin/sudo
InstallationDate: Installed on 2014-09-17 (702 days ago)
InstallationMedia: Ubuntu 14.04 LTS "Trusty Tahr" - Release amd64 (20140417)
ProcCmdline: /usr/bin/sudo -H -S -p GNOME_SUDO_PASS -u root -- nautilus
Signal: 5
SourcePackage: sudo
StacktraceTop:
 kill () at ../sysdeps/unix/syscall-template.S:84
 ?? ()
 __libc_start_main (main=0x5575cc03fa20, argc=9, argv=0x7ffd41508e28, init=<optimised out>, fini=<optimised out>, rtld_fini=<optimised out>, stack_end=0x7ffd41508e18) at ../csu/libc-start.c:291
 ?? ()
Title: sudo crashed with signal 5 in kill()
UpgradeStatus: Upgraded to xenial on 2016-08-18 (1 days ago)
UserGroups:

VisudoCheck:
 /etc/sudoers: parsed OK
 /etc/sudoers.d/README: parsed OK

[Apport retracing service (apport)]

StacktraceTop:
 kill () at ../sysdeps/unix/syscall-template.S:84
 main (argc=<optimized out>, argv=<optimized out>, envp=<optimized out>) at /build/sudo-L2mAoN/sudo-1.8.16/src/sudo.c:330