Num Lock light turns off when pressing Ctrl

After every reset when I press either Ctrl key (for example Ctrl+Alt+T to open the terminal) the Num Lock light turns off. The Shift key also has this effect. I have to press the Num Lock button twice to turn the light back on.

The Num Lock does work properly, inserting numbers as it should when pressing the keys, even with the indicator light off. This occurred on two different machines: a Dell Vostro 430 and a Lenovo m57.

The light should not turn off this way, of course, so pressing Ctrl should be fixed so that it doesn't affect the numeric keypad in this unusual way.

I had previously categorized this under "numlockx" package, but that was incorrect because numlockx was not even installed... I had originally made a wild attempt to identify the package because there is a lot of emphasis placed on naming the package containing the bug, but that is not always so easy to do (and when done is actually a major step in solving such elusive problems, isn't it?).

Ubuntu 16.04 LTS

ProblemType: Bug
DistroRelease: Ubuntu 16.04
ProcVersionSignature: Ubuntu 4.4.0-28.47-generic 4.4.13
Uname: Linux 4.4.0-28-generic x86_64
ApportVersion: 2.20.1-0ubuntu2.1
Architecture: amd64
CurrentDesktop: Unity
Date: Sat Jul 9 09:52:12 2016
InstallationDate: Installed on 2016-06-24 (14 days ago)
InstallationMedia: Ubuntu 16.04 LTS "Xenial Xerus" - Release amd64 (20160420.1)
---
ApportVersion: 2.20.1-0ubuntu2.1
Architecture: amd64
AudioDevicesInUse:
 USER PID ACCESS COMMAND
 /dev/snd/controlC1: dv430uuyn 2061 F.... pulseaudio
 /dev/snd/controlC0: dv430uuyn 2061 F.... pulseaudio
DistroRelease: Ubuntu 16.04
HibernationDevice: RESUME=UUID=e8206eff-651f-4207-b0a8-9c5a06959711
InstallationDate: Installed on 2016-06-24 (18 days ago)
InstallationMedia: Ubuntu 16.04 LTS "Xenial Xerus" - Release amd64 (20160420.1)
IwConfig:
 enp2s0 no wireless extensions.

 lo no wireless extensions.
MachineType: Dell Inc. Vostro 430
Package: linux (not installed)
ProcEnviron:
 LANGUAGE=en_CA:en
 TERM=xterm-256color
 PATH=(custom, no user)
 LANG=en_CA.UTF-8
 SHELL=/bin/bash
ProcFB: 0 nouveaufb
ProcKernelCmdLine: BOOT_IMAGE=/boot/vmlinuz-4.4.0-28-generic root=UUID=c3a8f971-548b-4666-b865-6bf917bef1c9 ro quiet splash vt.handoff=7
ProcVersionSignature: Ubuntu 4.4.0-28.47-generic 4.4.13
PulseList:
 Error: command ['pacmd', 'list'] failed with exit code 1: Home directory not accessible: Permission denied
 No PulseAudio daemon running, or not running as session daemon.
RelatedPackageVersions:
 linux-restricted-modules-4.4.0-28-generic N/A
 linux-backports-modules-4.4.0-28-generic N/A
 linux-firmware 1.157.2
RfKill:

Tags: xenial
Uname: Linux 4.4.0-28-generic x86_64
UpgradeStatus: No upgrade log present (probably fresh install)
UserGroups:

_MarkForUpload: True
dmi.bios.date: 01/13/2011
dmi.bios.vendor: Dell Inc.
dmi.bios.version: 2.4.0
dmi.board.name: 054KM3
dmi.board.vendor: Dell Inc.
dmi.board.version: A01
dmi.chassis.type: 3
dmi.chassis.vendor: Dell Inc.
dmi.modalias: dmi:bvnDellInc.:bvr2.4.0:bd01/13/2011:svnDellInc.:pnVostro430:pvr00:rvnDellInc.:rn054KM3:rvrA01:cvnDellInc.:ct3:cvr:
dmi.product.name: Vostro 430
dmi.product.version: 00
dmi.sys.vendor: Dell Inc.