That's not really a problem with ioFTPD. It's makecert complaining about something. Check the changelog to see how to run CertMgr as a MMC plugin and look for the certificate. Windows has a host of problems associated with it's cert store. Rebooting is often required to close existing open connections which allows an old cert to actually be freed and a new one with that name to be created...
From the comment of Immune_Hosts: List of space separated wildcard IP/hosts that are immune from banning. So yea, just put a space between them
