Server error when defining schedule (unicode)

Version: SVN r6658 on an Ubuntu Edgy
Problem: after choosing the periods for a schedule, I got an internal server error.

Almost all the strings used had non-ascii chars (timetable, section, course). So I can't pinpoint which one(s) caused this.

Exception:

UnicodeEncodeError: 'ascii' codec can't encode character u'\xed' in position 24: ordinal not in range(128)

Traceback:

File "/home/joao/testes/schooltool/schooltool/Zope3/src/zope/publisher/publish.py", line 133, in publish
  result = publication.callObject(request, obj)
File "/home/joao/testes/schooltool/schooltool/Zope3/src/zope/app/publication/zopepublication.py", line 161, in callObject
  return mapply(ob, request.getPositionalArguments(), request)
File "/home/joao/testes/schooltool/schooltool/Zope3/src/zope/publisher/publish.py", line 108, in mapply
  return debug_call(obj, args)
Extra information: <bound method SectionTimetableSetupView.__call__ of <zope.app.publisher.browser.viewmeta.SectionTimetableSetupView object at 0xb05c852c>>
File "/home/joao/testes/schooltool/schooltool/Zope3/src/zope/publisher/publish.py", line 114, in debug_call
  return obj(*args)
File "/home/joao/testes/schooltool/schooltool/src/schooltool/timetable/browser/__init__.py", line 654, in __call__
  day.add(period_id, act)
File "/home/joao/testes/schooltool/schooltool/src/schooltool/timetable/__init__.py", line 325, in add
  zope.event.notify(event)
File "/home/joao/testes/schooltool/schooltool/Zope3/src/zope/event/__init__.py", line 23, in notify
  subscriber(event)
File "/home/joao/testes/schooltool/schooltool/Zope3/src/zope/component/event.py", line 26, in dispatch
  for ignored in zope.component.subscribers(event, None):
File "/home/joao/testes/schooltool/schooltool/Zope3/src/zope/component/_api.py", line 130, in subscribers
  return sitemanager.subscribers(objects, interface)
File "/home/joao/testes/schooltool/schooltool/Zope3/src/zope/component/registry.py", line 290, in subscribers
  return self.adapters.subscribers(objects, provided)
File "/home/joao/testes/schooltool/schooltool/Zope3/src/zope/interface/adapter.py", line 535, in subscribers
  subscription(*objects)
File "/home/joao/testes/schooltool/schooltool/src/schooltool/timetable/model.py", line 397, in addEventsToCalendar
  calendar = timetable.model.createCalendar(term, timetable)
File "/home/joao/testes/schooltool/schooltool/src/schooltool/timetable/model.py", line 154, in createCalendar
  activity=activity)
File "/home/joao/testes/schooltool/schooltool/src/schooltool/timetable/model.py", line 346, in __init__
  CalendarEvent.__init__(self, *args, **kwargs)
File "/home/joao/testes/schooltool/schooltool/src/schooltool/app/cal.py", line 60, in __init__
  self.__name__ = base64.encodestring(self.unique_id).replace('\n', '')
File "base64.py", line 315, in encodestring
  pieces.append(binascii.b2a_base64(chunk))