aptdaemon crashed when booting in life usb session

[Ferran Rius]

I started a life session with an usb drive and I got a message telling me that aptdaemon crashed.
It's under Ubuntu 11.04, aptdaemon version 0.41+bzr646-0ubuntu2.

ProblemType: Crash
DistroRelease: Ubuntu 11.04
Package: aptdaemon 0.41+bzr646-0ubuntu2
ProcVersionSignature: Ubuntu 2.6.38-8.42-generic 2.6.38.2
Uname: Linux 2.6.38-8-generic i686
Annotation: Removing software failed
Architecture: i386
Date: Mon Jul 25 20:06:56 2011
DesktopFile: /usr/share/aptdaemon/aptdaemon.desktop
ExecutablePath: /usr/sbin/aptd
LiveMediaBuild: Ubuntu 11.04 "Natty Narwhal" - Release i386 (20110427.1)
PackageArchitecture: all
SourcePackage: aptdaemon
Title: <type 'exceptions.IOError'>: [Errno 2] No such file or directory: '/var/cache/apt/archives/lock'
TransactionDepends: [[], [], ['unity=3.8.16-0ubuntu1~natty1', 'libcompizconfig0=0.9.4-0ubuntu2', 'compizconfig-backend-gconf=0.9.2.4-0ubuntu1', 'compiz-plugins=1:0.9.4+bzr20110606-0ubuntu1~natty2', 'compiz-plugins-main=0.9.4+bzr20110527-0ubuntu1~natty1', 'compiz=1:0.9.4+bzr20110606-0ubuntu1~natty2', 'compiz-gnome=1:0.9.4+bzr20110606-0ubuntu1~natty2'], [], [], [], []]
TransactionErrorCode: error-unknown
TransactionKwargs: {}
TransactionLocale: ca_ES.UTF8
TransactionOutput:

TransactionPackages: [[], [], [dbus.String(u'compiz-core')], [], [], []]
TransactionRole: role-remove-packages
UpgradeStatus: No upgrade log present (probably fresh install)