Traceback (most recent call last):
  File "/usr/lib/python2.5/site-packages/pymsn/switchboard_manager.py", line 74, in <lambda>
    lambda sb, contact: self.__on_user_left(contact))
  File "/usr/lib/python2.5/site-packages/pymsn/switchboard_manager.py", line 135, in __on_user_left
    self.participants.remove(contact)
KeyError: <pymsn.Contact id='2f9ca7fd-c353-4f8f-9ed0-eddc05787b58' network='1' account='katleenverhaegen@hotmail.com' memberships='FORWARD | ALLOW | REVERSE'>