compiz does not terminate at computer shutdown

This is new/experimental installation of Ubuntu 13.10 Server on a QNAP SS839Pro NAS, about two weeks old.
The situation arose after:
  1. restarting the networking service (which lead to unresponsive/frozen Desktop)
  2. trying to "service lightdm restart" from the text console, which did not work and led to an (automatic) attempt to start it in low resolution graphics. This was cancelled, apache was stopped and I was preparing to switch to single user mode for maintenance.
  3. after a couple of minutes (working on another computer) the screen disappeared like going to sleep mode, although it is disabled in the (desktop's) system settings; could this be an ACPI problem? Pressing a key or trying to switch between tty[1-8] did not show any change on the (sleeping?) screen, although keyboard LEDs (CAPs, NumLock, etc.) seemed to switch when pressing the respective keys; ping from another machine was functioning.
  4. Ctrl+Alt+Del led to reboot.

NOTES:
  a) since this is a server, it has been restarted only a couple of times during the mentioned two weeks. Nevertheless I remember that shutting down used to take about 15" at the beginning, while it is taking longer and longer with the time and with installing more services on the system.
  b) until now I never managed to enter single user mode on this machine - both booting with kernel parameter "single" and issuing "telinit 1" led to hanging system.

I am not sure whether this is a bug or a "business like usual" situation, so I do not expect a "dedicated investigation", but any recommendations/hints will be highly appreciated!

Kind regards

ProblemType: Bug
DistroRelease: Ubuntu 13.10
Package: compiz-core 1:0.9.10+13.10.20131011-0ubuntu1
ProcVersionSignature: Ubuntu 3.11.0-14.21-generic 3.11.7
Uname: Linux 3.11.0-14-generic i686
NonfreeKernelModules: zfs zunicode zavl zcommon znvpair
.tmp.unity.support.test.0:

ApportVersion: 2.12.5-0ubuntu2.2
Architecture: i386
CompizPlugins: No value set for `/apps/compiz-1/general/screen0/options/active_plugins'
CompositorRunning: compiz
CompositorUnredirectDriverBlacklist: '(nouveau|Intel).*Mesa 8.0'
CompositorUnredirectFSW: true
Date: Fri Jan 17 07:19:38 2014
DistUpgraded: Fresh install
DistroCodename: saucy
DistroVariant: ubuntu
DkmsStatus:
 spl, 0.6.2, 3.11.0-14-generic, i686: installed
 zfs, 0.6.2, 3.11.0-14-generic, i686: installed
ExecutablePath: /usr/bin/compiz
GraphicsCard:
 Intel Corporation Mobile 945GSE Express Integrated Graphics Controller [8086:27ae] (rev 03) (prog-if 00 [VGA controller])
   Subsystem: Intel Corporation Mobile 945GSE Express Integrated Graphics Controller [8086:27ae]
   Subsystem: Intel Corporation Device [8086:27ae]
MachineType: ICP / iEi ATOM NAS
MarkForUpload: True
OmitPids: 1488 2064 11993 263 1558 11993 263
ProcCmdline: compiz
ProcEnviron:
 LANGUAGE=en_US:en
 PATH=(custom, no user)
 XDG_RUNTIME_DIR=<set>
 LANG=en_US.UTF-8
 SHELL=/bin/bash
ProcKernelCmdLine: BOOT_IMAGE=/vmlinuz-3.11.0-14-generic root=UUID=3efad279-91e0-4c1b-95a1-6f240a82b244 ro persistent vmalloc=700M
SourcePackage: compiz
Title: compiz does not terminate at computer shutdown
UpgradeStatus: No upgrade log present (probably fresh install)
dmi.bios.date: 11/19/2009
dmi.bios.vendor: American Megatrends Inc.
dmi.bios.version: 080015
dmi.board.asset.tag: To Be Filled By O.E.M.
dmi.board.name: ATOM NAS (QE05)
dmi.board.vendor: ICP / iEi
dmi.board.version: V1.0
dmi.modalias: dmi:bvnAmericanMegatrendsInc.:bvr080015:bd11/19/2009:svnICP/iEi:pnATOMNAS:pvrV1.0:rvnICP/iEi:rnATOMNAS(QE05):rvrV1.0:
dmi.product.name: ATOM NAS
dmi.product.version: V1.0
dmi.sys.vendor: ICP / iEi
version.compiz: compiz 1:0.9.10+13.10.20131011-0ubuntu1
version.libdrm2: libdrm2 2.4.46-1ubuntu1
version.libgl1-mesa-dri: libgl1-mesa-dri 9.2.1-1ubuntu3
version.libgl1-mesa-dri-experimental: libgl1-mesa-dri-experimental N/A
version.libgl1-mesa-glx: libgl1-mesa-glx 9.2.1-1ubuntu3
version.xserver-xorg-core: xserver-xorg-core 2:1.14.5-1ubuntu2~saucy1
version.xserver-xorg-input-evdev: xserver-xorg-input-evdev 1:2.7.3-0ubuntu3.1
version.xserver-xorg-video-ati: xserver-xorg-video-ati 1:7.2.0-0ubuntu10
version.xserver-xorg-video-intel: xserver-xorg-video-intel 2:2.99.904-0ubuntu2
version.xserver-xorg-video-nouveau: xserver-xorg-video-nouveau 1:1.0.9-2ubuntu1
xserver.bootTime: Fri Jan 17 07:20:59 2014
xserver.configfile: default
xserver.devices:
 input Power Button KEYBOARD, id 6
 input Power Button KEYBOARD, id 7
 input Logitech USB Keyboard KEYBOARD, id 8
 input Logitech USB Keyboard KEYBOARD, id 9
 input Logitech USB-PS/2 Optical Mouse MOUSE, id 10
xserver.errors:

xserver.logfile: /var/log/Xorg.0.log
xserver.outputs:
 product id 41005
 vendor DEL
xserver.version: 2:1.14.5-1ubuntu2~saucy1