too many open files

[Ragnar Beer <rbeer_(_at_)_uni-goettingen_(_dot_)_de>]

Help!

Zope 2.1.6 refuses to work in the middle of an external method on my 
i386 running under OpenBSD 2.7. Is says:
----------------------------------------------------
OSError
[Errno 24] Too many open files: '/var/tmp/@6067.265'
----------------------------------------------------

I've never ever seen this problem before and this external method 
used to work well until some minutes ago. Now the error keeps 
reappearing even after rebooting and also other external methods that 
used to run well now deliver the same message.

Does anybody have suggestions how to diagnose/cure this problem?

--Ragnar