Tried with another .RAR packed multy-file torrent, the result was the same type of corruption.
I then tried downloading a few .ISO files (images of different OS), the result was no corruption (the OS from the .ISO installed without a problem).
I hope there will be shed some light on the issue before too long.
[unofficial]qBittorrent git master builds: 3.3.0alpha_20150621_5e400d31174
Testing the freshly baked, latest builds!