ftp thread issues

When running naftpapp or my own app the ftp thread does not aways start. All other network services work (UDP/ping/telnet) 100% reliably. I call FSStartServer, it returns 0 but it has not started. I can call it manually and after a number of calls (1-5) it starts, then I can ftp. When it works I can see the FSV thread in the thread list. Martin