cannot unselect packages

Binary package hint: computer-janitor

If I start computer-janitor-gtk from a terminal on up to date natty, I cannot unselect packages. Here is terminal output from when I click on a checkbox to unselect it.

$ computer-janitor-gtk
/usr/share/computerjanitor/computerjanitorapp/gtk/ui.py:94: GtkWarning: Could not load image 'computerjanitor-24x24.png': Failed to open file '/usr/share/computer-janitor/computerjanitor-24x24.png': No such file or directory
  builder.add_from_file(glade_file)
ERROR:dbus.proxies:Introspect error on :1.136:/: dbus.exceptions.DBusException: org.freedesktop.DBus.Error.AccessDenied: Rejected send message, 1 matched rules; type="method_call", sender=":1.138" (uid=1000 pid=11325 comm="/usr/bin/python) interface="org.freedesktop.DBus.Introspectable" member="Introspect" error name="(unset)" requested_reply=0 destination=":1.136" (uid=0 pid=10718 comm="/usr/bin/python))
Traceback (most recent call last):
  File "/usr/share/computerjanitor/computerjanitorapp/gtk/ui.py", line 374, in _toggled
    self.janitord.ignore(cruft_name)
  File "/usr/lib/pymodules/python2.6/dbus/proxies.py", line 140, in __call__
    **keywords)
  File "/usr/lib/pymodules/python2.6/dbus/connection.py", line 630, in call_blocking
    message, timeout)
dbus.exceptions.DBusException: org.freedesktop.PolicyKit1.Error.Failed: Error getting subject: Error parsing unix-process subject: Value for key `start-time' found but is of type i and type t was expected