Hi Helmut. Sorry. I have just noticed your mail. Well, yes, I have found a solution (although it is more like a workaround). The problem was that the following python statement self.erzeuger = AUTHENTICATED_USER within the constructor of my python-base class SOMEHOW shot the thing and I was unable to get a hand on it anymore (even trying to get these things out manually (but that was another problem ;) So, I changed the line to: self.erzeuger = AUTHENTICATED_USER.getUserName() since all I needed was the name! That solved it. I got a similiar thing as I once tried to assign an empty list to an object-member in a xxx_add method by <dtml-call "REQUEST.set('me', [])"> the result was exactly the same: an object got created and changed its type to the type of the container class after a few (non-deterministic) accesses. Did this with zope 2.1.4/2.1.5/2.1.6 on linux/i386 and win32. Reproducable. hmmm... bogus. Perhaps a bug in the persistence mechamism?? I do not know. But I do avoid those assignments (although they are not forbidden, are they?) Interesting to notice: you can use those assignments within methods when you do not store anything. Sorry for the late answer. Regards, Ingo.
I've noticed your mail on zope@zope.org becaus I'm in the same troubles.
If you've got a solution for this problem, please contact me or repost it at zope@zope.org.