[Zope] FTP crashing Zope?

Hello! I have latest Zope, buitl from source on a RedHat 6.2 machine. Using FTP Explorer I crashed (killed) my Zope instance while ftping in to port 8021. This was achieved by not setting FTP Explorer to use PASSIVe connections. Using Passive it works like a charm. Is this a bug in latest Zope (2.2.1) or is this expected behaviour? If, the latter is the case, what can I do to a) turn off FTP access, b) make sure that my Zope is up and running automagically after a crash? Thnx /Dario