I am having the exact same problem with nxtools, i did think i found a fix but it didnt help at all. Maby you can try and add this fix and maby it helps on youre end.
MP3 PRE dzsbot Annouce Question - FlashFXP Forums
the fix can you find at the bottom of that page, but i tired it and it didnt work for me with nxtools 1.2.1 and ioftpd 7.7.3 and ioninja beta 4
If anyone have a fix or help please its bugging me to not be able to fix this error.