I've been having various problems with newsbin for a few months with failed downloads, I've been thinking it's because the files are incomplete but it's not.
Just did a test on one nzb containing 5 rars, it downloaded part1 and part2 fine as I ran the par2 in multipar and they both passed the checks fine.
I closed multipar down and waited for the download to complete....and I got a Critical Error Popup from newsbin.
ERROR DecodeException: - Decode Failed - Download all PARS:
The par2 files and part1 and part2 rars have been deleted by newsbin, though part 3,4, & 5 exist.
I fed the nzb into a freeware nzb downloader and it worked fine.
Newsdemon server
Newsbin 6.90 Release - build 5524 (tried on this, but ive been having the problem for a while - just never thought it was newsbin)
Any ideas?