icons stuck at top of unity dash

Unity version: 4.28.0-0ubuntu2 on 11.10

00:02.1 Display controller: Intel Corporation Mobile 945GM/GMS/GME, 943/940GML Express Integrated Graphics Controller (rev 03)

This has happened sporadically since before upgrading to 11.10, and seems to happen after a period of idle, though I seem to recollect it happening with minimal idle time previously. I have no idea how to reproduce it, other than wait for it to appear.

The screenshot attached is probably the best way to see what's happened.

* All the icons are stuck at the top of the dash, layered upon each other, and translucent. see screenshot
* The clickable area for the bottom few are still available beneath the pile of icons, as seen in the screenshot, though the tooltip bubble is out of alignment. see screenshot
* alt-tab still works as intended
* meta/windows key still brings up the menu as intended

The only way to get out of this without losing unity settings seem to be to restart the computer. If I'm wrong about this, I'd welcome being corrected.

ProblemType: Bug
DistroRelease: Ubuntu 11.10
Package: xorg 1:7.6+7ubuntu7.1
ProcVersionSignature: Ubuntu 3.0.0-15.26-generic 3.0.13
Uname: Linux 3.0.0-15-generic i686
NonfreeKernelModules: wl
.tmp.unity.support.test.0:

ApportVersion: 1.23-0ubuntu4
Architecture: i386
CompizPlugins: [core,bailer,detection,composite,opengl,decor,regex,compiztoolbox,resize,mousepoll,imgpng,gnomecompat,snap,grid,move,vpswitch,unitymtgrabhandles,place,wall,animation,expo,session,fade,workarounds,scale,ezoom,unityshell]
CompositorRunning: compiz
Date: Fri Mar 23 20:37:02 2012
DistUpgraded: Log time: 2011-12-25 14:23:54.928807
DistroCodename: oneiric
DistroVariant: ubuntu
DkmsStatus:
 bcmwl, 5.100.82.38+bdcom, 2.6.38-13-generic, i686: installed
 bcmwl, 5.100.82.38+bdcom, 3.0.0-14-generic, i686: installed
 bcmwl, 5.100.82.38+bdcom, 3.0.0-15-generic, i686: installed
 bcmwl, 5.100.82.38+bdcom, 3.0.0-16-generic, i686: installed
ExtraDebuggingInterest: Yes, whatever it takes to get this fixed in Ubuntu
GraphicsCard:
 Intel Corporation Mobile 945GME Express Integrated Graphics Controller [8086:27ae] (rev 03) (prog-if 00 [VGA controller])
   Subsystem: Hewlett-Packard Company Device [103c:308f]
   Subsystem: Hewlett-Packard Company Device [103c:308f]
InstallationMedia: Ubuntu-Netbook 10.10 "Maverick Meerkat" - Release i386 (20101007)
MachineType: Hewlett-Packard HP Mini 110-1000
ProcEnviron:
 PATH=(custom, no user)
 LANG=en_NZ.UTF-8
 SHELL=/bin/bash
ProcKernelCmdLine: BOOT_IMAGE=/boot/vmlinuz-3.0.0-15-generic root=UUID=c8695f53-38ad-438e-99dc-3c890960c9f6 ro quiet splash vt.handoff=7
SourcePackage: xorg
Symptom: display
UpgradeStatus: Upgraded to oneiric on 2011-12-25 (89 days ago)
dmi.bios.date: 06/18/2009
dmi.bios.vendor: Hewlett-Packard
dmi.bios.version: 308F0 Ver. F.07
dmi.board.name: 308F
dmi.board.vendor: Hewlett-Packard
dmi.board.version: KBC Version 02.0B
dmi.chassis.asset.tag: CNU9328M4H
dmi.chassis.type: 10
dmi.chassis.vendor: Hewlett-Packard
dmi.modalias: dmi:bvnHewlett-Packard:bvr308F0Ver.F.07:bd06/18/2009:svnHewlett-Packard:pnHPMini110-1000:pvr03A8100000000000100300000:rvnHewlett-Packard:rn308F:rvrKBCVersion02.0B:cvnHewlett-Packard:ct10:cvr:
dmi.product.name: HP Mini 110-1000
dmi.product.version: 03A8100000000000100300000
dmi.sys.vendor: Hewlett-Packard
version.compiz: compiz 1:0.9.6+bzr20110929-0ubuntu6.1
version.libdrm2: libdrm2 2.4.26-1ubuntu1
version.libgl1-mesa-dri: libgl1-mesa-dri 7.11-0ubuntu3
version.libgl1-mesa-dri-experimental: libgl1-mesa-dri-experimental N/A
version.libgl1-mesa-glx: libgl1-mesa-glx 7.11-0ubuntu3
version.xserver-xorg: xserver-xorg 1:7.6+7ubuntu7.1
version.xserver-xorg-input-evdev: xserver-xorg-input-evdev 1:2.6.0-1ubuntu13
version.xserver-xorg-video-ati: xserver-xorg-video-ati 1:6.14.99~git20110811.g93fc084-0ubuntu1
version.xserver-xorg-video-intel: xserver-xorg-video-intel 2:2.15.901-1ubuntu2.1
version.xserver-xorg-video-nouveau: xserver-xorg-video-nouveau 1:0.0.16+git20110411+8378443-1