No mouse pointer or cursor displayed

[Rocko]

This VM running Ubuntu 15.10 used to display a mouse cursor, but after upgrades today it no longer does, even after a full reboot (or several, in fact). Target components (buttons etc) change when the mouse are over them to indicate they will receive the mouse click, but there is no mouse pointer displayed, or cursor when in gnome-terminal or text boxes, etc.

The host Ubuntu 15.10 system that the VM is running on usually displays a mouse pointer, but sometimes it stops doing so. Occasionally this can be fixed by switching to a virtual terminal (CTRL-ALT-F1) and back, and if this doesn't work restarting compiz and unity manually (with compiz --replace and unity --replace) may fix the problem, although not always.

ProblemType: Bug
DistroRelease: Ubuntu 15.10
Package: compiz 1:0.9.12.2+15.10.20151015-0ubuntu1
ProcVersionSignature: Ubuntu 4.2.0-19.23-generic 4.2.6
Uname: Linux 4.2.0-19-generic x86_64
.tmp.unity.support.test.0:

ApportVersion: 2.19.1-0ubuntu5
Architecture: amd64
CompizPlugins: No value set for `/apps/compiz-1/general/screen0/options/active_plugins'
CompositorRunning: compiz
CompositorUnredirectDriverBlacklist: '(nouveau|Intel).*Mesa 8.0'
CompositorUnredirectFSW: true
CurrentDesktop: Unity
Date: Mon Dec 14 09:47:24 2015
DistUpgraded: Fresh install
DistroCodename: wily
DistroVariant: ubuntu
GraphicsCard: InnoTek Systemberatung GmbH VirtualBox Graphics Adapter [80ee:beef] (prog-if 00 [VGA controller])
InstallationDate: Installed on 2015-10-28 (46 days ago)
InstallationMedia: Ubuntu 15.10 "Wily Werewolf" - Release amd64 (20151021)
Lsusb:
 Bus 001 Device 001: ID 1d6b:0002 Linux Foundation 2.0 root hub
 Bus 002 Device 002: ID 80ee:0021 VirtualBox USB Tablet
 Bus 002 Device 001: ID 1d6b:0001 Linux Foundation 1.1 root hub
MachineType: innotek GmbH VirtualBox
PackageArchitecture: all
ProcKernelCmdLine: BOOT_IMAGE=/boot/vmlinuz-4.2.0-19-generic root=UUID=dd9670b8-05a7-40de-87ea-97125d5254ce ro quiet splash
Renderer: Software
SourcePackage: compiz
UdevLog: Error: [Errno 2] No such file or directory: '/var/log/udev'
UpgradeStatus: No upgrade log present (probably fresh install)
dmi.bios.date: 12/01/2006
dmi.bios.vendor: innotek GmbH
dmi.bios.version: VirtualBox
dmi.board.name: VirtualBox
dmi.board.vendor: Oracle Corporation
dmi.board.version: 1.2
dmi.chassis.type: 1
dmi.chassis.vendor: Oracle Corporation
dmi.modalias: dmi:bvninnotekGmbH:bvrVirtualBox:bd12/01/2006:svninnotekGmbH:pnVirtualBox:pvr1.2:rvnOracleCorporation:rnVirtualBox:rvr1.2:cvnOracleCorporation:ct1:cvr:
dmi.product.name: VirtualBox
dmi.product.version: 1.2
dmi.sys.vendor: innotek GmbH
version.compiz: compiz 1:0.9.12.2+15.10.20151015-0ubuntu1
version.ia32-libs: ia32-libs N/A
version.libdrm2: libdrm2 2.4.64-1
version.libgl1-mesa-dri: libgl1-mesa-dri 11.0.2-1ubuntu4
version.libgl1-mesa-dri-experimental: libgl1-mesa-dri-experimental N/A
version.libgl1-mesa-glx: libgl1-mesa-glx 11.0.2-1ubuntu4
version.xserver-xorg-core: xserver-xorg-core 2:1.17.2-1ubuntu9.1
version.xserver-xorg-input-evdev: xserver-xorg-input-evdev 1:2.9.2-1ubuntu1
version.xserver-xorg-video-ati: xserver-xorg-video-ati 1:7.5.0+git20150819-0ubuntu1
version.xserver-xorg-video-intel: xserver-xorg-video-intel 2:2.99.917+git20150808-0ubuntu4
version.xserver-xorg-video-nouveau: xserver-xorg-video-nouveau 1:1.0.11-1ubuntu3
xserver.bootTime: Mon Dec 14 09:46:31 2015
xserver.configfile: default
xserver.errors:
 open /dev/fb0: No such file or directory
 AIGLX error: vboxvideo does not export required DRI extension
 AIGLX: reverting to software rendering
xserver.logfile: /var/log/Xorg.0.log
xserver.outputs:

xserver.version: 2:1.17.2-1ubuntu9.1

[Rocko (rockorequin)]

I managed to trigger it today by removing an external monitor - after the screen changed configuration, the mouse pointer was gone. Restarting unity fixed it.