[Zope] Zope produce core file

Hi, I have a problem with zope. im using the Zope 2.5.0 (i downloaded the binary version from zope site). and once in a while zope just dies producing a core file with no log messages. I have it as a fastcgi under cobalt with apache 1.3.20. anyone had the same problem?? thanks in advance, Eyal.