I'm sure the problem is in zipscript. Before ioBanana i used ioZS and have it in /scripts/ folder. To check i just modify ioftpd.ini file and check ioZS as checker - and everything good, it comes t 100% when i refill files (coz banana deletes bad, even with delete=0 checked).
I dunno where to find unzip exe, but i'm perfectly unpacked "BAD" file with WinRAR, Total Commander and Windows internal zip-packer. Everything was OK. But this file ioBanana don't want to save and checks as bad. Only this one file of all release (one of 6).
As i see, every day about 10 releases like that.