django незакономерное возникновение 500 ошибки

[Tue Nov 30 15:51:56 2010] [error] [client 127.0.0.1] mod_wsgi (pid=16110): Exception occurred within WSGI script '/var/www/vhosts/data/www/data.wsgi'.
[Tue Nov 30 15:51:56 2010] [error] [client 127.0.0.1] Traceback (most recent call last):
[Tue Nov 30 15:51:56 2010] [error] [client 127.0.0.1]   File "/usr/lib/python2.5/site-packages/django/core/handlers/wsgi.py", line 241, in __call__
[Tue Nov 30 15:51:56 2010] [error] [client 127.0.0.1]     response = self.get_response(request)
[Tue Nov 30 15:51:56 2010] [error] [client 127.0.0.1]   File "/usr/lib/python2.5/site-packages/django/core/handlers/base.py", line 141, in get_response
[Tue Nov 30 15:51:56 2010] [error] [client 127.0.0.1]     return self.handle_uncaught_exception(request, resolver, sys.exc_info())
[Tue Nov 30 15:51:56 2010] [error] [client 127.0.0.1]   File "/usr/lib/python2.5/site-packages/django/core/handlers/base.py", line 164, in handle_uncaught_exception
[Tue Nov 30 15:51:56 2010] [error] [client 127.0.0.1]     from django.views import debug
[Tue Nov 30 15:51:56 2010] [error] [client 127.0.0.1] ImportError: cannot import name debug