Unity crash on Alt+Tab

Binary package hint: unity

On my machine, Unity systematically crashes when pressing Alt+Tab.
Running an up to date Natty.

ProblemType: Bug
DistroRelease: Ubuntu 11.04
Package: unity 3.2.8-0ubuntu1
ProcVersionSignature: Ubuntu 2.6.37-11.25-generic 2.6.37-rc7
Uname: Linux 2.6.37-11-generic x86_64
Architecture: amd64
CompizPlugins: No value set for `/apps/compiz-1/general/allscreens/options/active_plugins'
Date: Wed Jan 5 22:10:24 2011
InstallationMedia: Kubuntu 10.04 "Lucid Lynx" - Alpha amd64 (20100322)
InstallationMedia_: Kubuntu 10.04 "Lucid Lynx" - Alpha amd64 (20100322)
MachineType: LENOVO 287655G
PciDisplay: 01:05.0 VGA compatible controller [0300]: ATI Technologies Inc RS780M/RS780MN [Radeon HD 3200 Graphics] [1002:9612] (prog-if 00 [VGA controller])
ProcEnviron:
 LANGUAGE=fr_FR:fr:en_GB:en
 LANG=fr_FR.utf8
 LC_MESSAGES=fr_FR.utf8
 SHELL=/bin/bash
ProcKernelCmdLine: BOOT_IMAGE=/boot/vmlinuz-2.6.37-11-generic root=UUID=9d1e1d6f-7448-4445-a811-8356280aba0c ro vt.handoff=7 quiet splash
ProcVersionSignature_: Ubuntu 2.6.37-11.25-generic 2.6.37-rc7
RelatedPackageVersions:
 xserver-xorg 1:7.5+6ubuntu6
 libgl1-mesa-glx 7.9+repack-1ubuntu3
 libdrm2 2.4.22-2ubuntu1
 xserver-xorg-video-intel 2:2.13.901-2ubuntu2
 xserver-xorg-video-ati 1:6.13.2-1ubuntu2
SourcePackage: unity
XorgConf: Error: [Errno 2] Aucun fichier ou dossier de ce type: '/etc/X11/xorg.conf'
dmi.bios.date: 01/13/2010
dmi.bios.vendor: LENOVO
dmi.bios.version: 6XET31WW (1.10a)
dmi.board.name: INVALID
dmi.board.vendor: LENOVO
dmi.board.version: Not Available
dmi.chassis.asset.tag: No Asset Information
dmi.chassis.type: 10
dmi.chassis.vendor: LENOVO
dmi.chassis.version: Not Available
dmi.modalias: dmi:bvnLENOVO:bvr6XET31WW(1.10a):bd01/13/2010:svnLENOVO:pn287655G:pvrThinkPadX100e:rvnLENOVO:rnINVALID:rvrNotAvailable:cvnLENOVO:ct10:cvrNotAvailable:
dmi.product.name: 287655G
dmi.product.version: ThinkPad X100e
dmi.sys.vendor: LENOVO
system: distro = Ubuntu, architecture = x86_64, kernel = 2.6.37-11-generic