TemplateSyntaxError at /admin/agenda/event/1/

Caught ViewDoesNotExist while rendering: Could not import agenda.views.vobject_django. Error was: No module named _thread

> python
Python 2.6.7 (r267:88850, Jul 12 2011, 11:28:50) 
[GCC 4.2.1 20070719  [FreeBSD]] on freebsd8
Type "help", "copyright", "credits" or "license" for more information.
>>> import _thread
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
ImportError: No module named _thread

# python
Python 2.6.5 (r265:79063, Apr 16 2010, 13:57:41) 
[GCC 4.4.3] on linux2
Type "help", "copyright", "credits" or "license" for more information.
>>> import _thread
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
ImportError: No module named _thread

    57,68c57,66
    <   {% if year %}
    <       <a href="{% url agenda-archive-year previous_year %}">{{ previous_year}}</a>
    <       <a href="{% url agenda-archive-year next_year %}">{{ next_year }}</a>
    <       <h1>{{ year }}</h1>
    <       {% if months %}
    <           <ul>
    <           {% for month in months %}
    <               <li><a href="{% url agenda-archive-month month.year month.month %}">{{ month|date:"M Y"}}</a></li>
    <           {% endfor %}
    <           </ul>
    <       {% endif %}
    <   {% endif %}
    ---
    >         <a href="{% url agenda-archive-year previous_year %}">{{ previous_year }}</a>
    >         <a href="{% url agenda-archive-year next_year %}">{{ next_year }}</a>
    >         <h1>{{ year }}</h1>
    >         {% if months %}
    >             <ul>
    >             {% for month in months %}
    >                 <li><a href="{% url agenda-archive-month month.year month.month %}">{{ month|date:"M Y"}}</a></li>
    >             {% endfor %}
    >             </ul>
    >         {% endif %}