computer janitor crashed with "Introspect error"

Binary package hint: computer-janitor

trying to use computer-janitor using the window i get the following error msg:

"Das Äufräumen des Systems konnte nicht abgeschlossen werden. Stellen Sie sicher, dass keine andere Paketverwaltung, wie Synaptic oder die Aktualisierungsverwaltung, läuft."
=
"the cleaning could not be finished. Please make sure, that no other package-service, like Synaptic or the update-manager is running."

more information seems to be given by the text mode:

jakub@jakub-laptop:~$ sudo computer-janitor clean --all
ERROR:dbus.proxies:Introspect error on :1.77:/: dbus.exceptions.DBusException: org.freedesktop.DBus.Error.AccessDenied: Rejected send message, 1 matched rules; type="method_call", sender=":1.84" (uid=0 pid=2716 comm="/usr/bin/python) interface="org.freedesktop.DBus.Introspectable" member="Introspect" error name="(unset)" requested_reply=0 destination=":1.77" (uid=0 pid=2573 comm="/usr/bin/python))
ERROR:dbus.connection:Unable to set arguments (set([dbus.String(u'deb:linux-image-2.6.37-3-generic'), dbus.String(u'deb:linux-headers-2.6.37-5-generic'), dbus.String(u'deb:icoutils'), dbus.String(u'deb:linux-image-2.6.37-6-generic'), dbus.String(u'deb:linux-image-2.6.37-4-generic'), dbus.String(u'deb:libmpg123-0'), dbus.String(u'deb:linux-image-2.6.37-5-generic'), dbus.String(u'deb:libgladeui-1-9'), dbus.String(u'deb:winbind'), dbus.String(u'deb:libexiv2-6'), dbus.String(u'deb:linux-headers-2.6.37-4-generic'), dbus.String(u'deb:linux-headers-2.6.35-22')]),) according to signature None: <type 'exceptions.TypeError'>: Don't know how which D-Bus type to use to encode type "set"
Traceback (most recent call last):
  File "/usr/sbin/computer-janitor", line 35, in <module>
    main()
  File "/usr/share/computerjanitor/computerjanitorapp/cli/main.py", line 312, in main
    options.arguments.func(options.arguments)
  File "/usr/share/computerjanitor/computerjanitorapp/cli/main.py", line 293, in clean
    timeout=3600)
  File "/usr/lib/pymodules/python2.6/dbus/proxies.py", line 132, in __call__
    **keywords)
  File "/usr/lib/pymodules/python2.6/dbus/connection.py", line 566, in call_async
    message.append(signature=signature, *args)
TypeError: Don't know how which D-Bus type to use to encode type "set"

this all is set in todays natty setup but has been present before, too
(proposed-repo)