[lucid] Can't bring up the window menu

Binary package hint: metacity

Since today's update I can't bring up the window menu anymore in lucid. Something weird happens, as if all virtual desktops are temporarily gone.

I have attached a video showing it (recorded with gtk-recordmydesktop). You can see a browser window flashing in the screen for a few moments: that window was on virtual desktop 6, while the terminal I'm showing the bug is from virtual desktop 2, so it's like for a while all windows are being shown in the current virtual desktop. And no window menu ever appears, so I can't move windows to other desktops anymore.

ProblemType: Bug
DistroRelease: Ubuntu 10.04
Package: metacity 1:2.30.0-0ubuntu1
ProcVersionSignature: Ubuntu 2.6.32-19.28-generic-pae 2.6.32.10+drm33.1
Uname: Linux 2.6.32-19-generic-pae i686
NonfreeKernelModules: nvidia
Architecture: i386
Date: Fri Apr 9 13:07:38 2010
InstallationMedia: Error: [Errno 13] Permission denied: '/var/log/installer/media-info'
ProcEnviron:
 PATH=(custom, user)
 LANG=en_US.utf8
 SHELL=/bin/bash
SourcePackage: metacity