Om någon råkar ut för samma proble hittade jag lösningen i en kommentar på Versiontracker:
gregornobis
I had the same problem with PureFTPd Manager crashing on startup. From the crash log I figured that the crash was caused by a thread that controlled user stats. I searched for the logfiles, deleted them and -tada!- manager is back up and working with only the stats missing.
I deleted files named ftp.log*, pureftpd.log, FTPStats.plist from
/private/var/log/