
Since I'm not that good in technical aspects I just tried something else: Now I've upgraded Ubuntu once again to the upcoming 13.04 which uses libtorrent 0.16.7.0 and... Deluge works like a charm again

-> http://dev.deluge-torrent.org/wiki/ReleaseNotes/1.1.3We are no longer providing packages, only the source tarballs
-> http://dev.deluge-torrent.org/wiki/ReleaseNotes/1.1.3We are no longer providing packages, only the source tarballs