I am really ashamed :(
The error was a bug in psycopg. His author warned me a few days ago about a
severe bug that was recently fixed and urged me to sync what I didn't did until
today.
The problem was caused by DictRow objects which where stored in all my Storable
objects. I don't know the details of the psycopg bug but after synching with his
source the problem has gone away. It is also possible that the other bug, the
one happening at 30 mins intervals is algo gone for good.
I'm really sorry. I won't bother you guys until I'm dead sure it's mod_python
related and until I have a testcase for it from the beginning.
Thank you all for your help.
--
dharana