[Zope] InterfaceError: already closed

[Jeff Gentry]

I have a Product which uses ZPsycoPG (and thus psycopg), currently running
on 3 systems.  On two of them I never see this, but on the third I get
intermittent errors of the nature: "Interface Error: already
closed".  These errors strike pretty much from any area that access the
DB, and "solving" the issue seems as simple as hitting the back button and
trying again (and I'm currently using the standard_error_message to fire
these back to a more user friendly page explaining this).  It would be
nice to make these simply go away though :)

I've seen a few references here and there that such errors might be
related to firewalls/proxying, and the affected host definitely is in such
an environment, but I don't know that I buy that this is what is going
on.  Is anyone familiar with this problem, and if so, any ideas as to
where to look?

Thanks
-J