cmf: thanx for solving my problem!
Some costumers were complaining their transfers were stalled at 100% (when the FTP server normally gives them a directory listing).
The problem was a 300second timeout of TCP ports on the hardware router.. Changed it to 3600s.. Not sure if this might affect anything else?
Sidenote: this is (was) not a flashfxp related problem.. Several (all?) ftp clients had the same problem.. I suspected Guildftpd at first.