Error and trace.
http://www.parsed.org/paste/13/
Pertinent models.
http://www.parsed.org/paste/14/
I'm using svn trunk version of Django and Python 2.5 on Windows.
I suspect you've hit #4562, which I'm pretty sure I'll be fixing today.
Regards,
Malcolm
--
Experience is something you don't get until just after you need it.
http://www.pointy-stick.com/blog/