Key stuck down causes compiz 100% cpu, PC unusable

At the lock screen if you leave a key down - perhaps a cat sat on the keyboard - for long enough (some minutes) will result in compiz hitting 100% and the lock screen is unusable.

To reproduce.

1) Lock screen
2) Hold down key for 20 minutes or more
3) Press escape to clear the password input field - fails
4) Attempt to click indicators - fails.

Expect to be able to clear the input field with escape, and be able to click other icons in the indicator.

ProblemType: Bug
DistroRelease: Ubuntu 14.10
Package: compiz 1:0.9.12+14.10.20140918-0ubuntu1
ProcVersionSignature: Ubuntu 3.16.0-23.31-generic 3.16.4
Uname: Linux 3.16.0-23-generic x86_64
NonfreeKernelModules: nvidia
.proc.driver.nvidia.gpus.0: Error: [Errno 21] Is a directory: '/proc/driver/nvidia/gpus/0'
.proc.driver.nvidia.registry: Binary: ""
.proc.driver.nvidia.version:
 NVRM version: NVIDIA UNIX x86_64 Kernel Module 331.89 Tue Jul 1 13:30:18 PDT 2014
 GCC version: gcc version 4.9.1 (Ubuntu 4.9.1-16ubuntu6)
ApportVersion: 2.14.7-0ubuntu8
Architecture: amd64
BootLog:
 Scanning for Btrfs filesystems
  * Setting sensors limits 
[ OK ]
  * Setting up X socket directories... 
[ OK ]
CompizPlugins: No value set for `/apps/compiz-1/general/screen0/options/active_plugins'
Date: Tue Nov 4 16:37:17 2014
DistUpgraded: Fresh install
DistroCodename: utopic
DistroVariant: ubuntu
EcryptfsInUse: Yes
GraphicsCard:
 NVIDIA Corporation GF104 [GeForce GTX 460] [10de:0e22] (rev a1) (prog-if 00 [VGA controller])
   Subsystem: Gigabyte Technology Co., Ltd Device [1458:34fc]
InstallationDate: Installed on 2012-01-02 (1037 days ago)
InstallationMedia: Ubuntu 12.04 LTS "Precise Pangolin" - Alpha amd64 (20120102)
MachineType: MSI MS-7680
PackageArchitecture: all
ProcKernelCmdLine: BOOT_IMAGE=/boot/vmlinuz-3.16.0-23-generic root=UUID=3d53ca44-6af4-422d-b1b0-adf30c679a2f ro quiet splash i915.semaphores=0
SourcePackage: compiz
UpgradeStatus: No upgrade log present (probably fresh install)
dmi.bios.date: 01/10/2013
dmi.bios.vendor: American Megatrends Inc.
dmi.bios.version: V12.3
dmi.board.asset.tag: To be filled by O.E.M.
dmi.board.name: H61M-E23(B3)(MS-7680)
dmi.board.vendor: MSI
dmi.board.version: 2.0
dmi.chassis.asset.tag: To Be Filled By O.E.M.
dmi.chassis.type: 3
dmi.chassis.vendor: MSI
dmi.chassis.version: 2.0
dmi.modalias: dmi:bvnAmericanMegatrendsInc.:bvrV12.3:bd01/10/2013:svnMSI:pnMS-7680:pvr2.0:rvnMSI:rnH61M-E23(B3)(MS-7680):rvr2.0:cvnMSI:ct3:cvr2.0:
dmi.product.name: MS-7680
dmi.product.version: 2.0
dmi.sys.vendor: MSI
version.compiz: compiz 1:0.9.12+14.10.20140918-0ubuntu1
version.ia32-libs: ia32-libs N/A
version.libdrm2: libdrm2 2.4.56-1
version.libgl1-mesa-dri: libgl1-mesa-dri 10.3.0-0ubuntu3
version.libgl1-mesa-dri-experimental: libgl1-mesa-dri-experimental 10.0.1-1ubuntu2
version.libgl1-mesa-glx: libgl1-mesa-glx 10.3.0-0ubuntu3
version.nvidia-graphics-drivers: nvidia-graphics-drivers N/A
version.xserver-xorg-core: xserver-xorg-core 2:1.16.0-1ubuntu1
version.xserver-xorg-input-evdev: xserver-xorg-input-evdev 1:2.9.0-1ubuntu2
version.xserver-xorg-video-ati: xserver-xorg-video-ati 1:7.4.0-2ubuntu2
version.xserver-xorg-video-intel: xserver-xorg-video-intel 2:2.99.914-1~exp1ubuntu4
version.xserver-xorg-video-nouveau: xserver-xorg-video-nouveau 1:1.0.11-1ubuntu2
xserver.bootTime: Tue Nov 4 10:33:20 2014
xserver.configfile: default
xserver.errors: open /dev/fb0: No such file or directory
xserver.logfile: /var/log/Xorg.0.log
xserver.outputs:

xserver.version: 2:1.16.0-1ubuntu1