Update Manger could not complete update

[Fabio M. Panico]

The update manager could not finish an update task, exiting with the following error message (french):

"Une erreur impossible à traiter est survenue. Il semble qu'il y ait une anomalie dans aptdeamon, le logiciel qui vous permet d'installer/désinstaller des applications et de réaliser d'autres tâches de gestion des paquets. Veuillez signaler cette erreur sur http://launchpad.net/aptdaemon/+filebug et réessayez"

(free translation: ""An untreatable error occurred. It seems there is an anomaly in aptdeamon, the software that lets you install / uninstall applications and perform other management tasks packets. Please report this error http://launchpad.net/aptdaemon/+filebug and try again")

The details provided by the application were:

"Traceback (most recent call last):
  File "/usr/lib/python2.6/dist-packages/aptdaemon/worker.py", line 179, in _process_transaction
    self.commit_packages(*self.trans.packages)
  File "/usr/lib/python2.6/dist-packages/aptdaemon/worker.py", line 227, in commit_packages
    self._commit_changes()
  File "/usr/lib/python2.6/dist-packages/aptdaemon/worker.py", line 738, in _commit_changes
    self._cache.commit(fetch_progress, inst_progress)
  File "/usr/lib/python2.6/dist-packages/apt/deprecation.py", line 98, in deprecated_function
    return func(*args, **kwds)
  File "/usr/lib/python2.6/dist-packages/apt/cache.py", line 427, in commit
    res = self.install_archives(pm, install_progress)
  File "/usr/lib/python2.6/dist-packages/apt/deprecation.py", line 98, in deprecated_function
    return func(*args, **kwds)
  File "/usr/lib/python2.6/dist-packages/apt/cache.py", line 394, in install_archives
    install_progress.finish_update()
  File "/usr/lib/python2.6/dist-packages/aptdaemon/progress.py", line 264, in finish_update
    lock.status_lock.acquire()
  File "/usr/lib/python2.6/dist-packages/aptdaemon/lock.py", line 66, in acquire
    raise LockFailedError(self.path, process)
LockFailedError"

Thank you for your time and patience to review this. Below I provide some basic information on the system, please advice whether any other could be provided to help treat this matter.

$ uname -a
Linux fujitsu 2.6.35-22-generic #35-Ubuntu SMP Sat Oct 16 20:36:48 UTC 2010 i686 GNU/Linux