Once I encontered very odd behavior of ktorrent. I had a fully downloaded torrent with >20 files, I deleted it from list and then readded. But when readding I selected none of files inside torrent, also selected "manual control" and "Start torrent". When I pressed OK ktorrent just deleted all corresponding files. I think ktorrent shouldnt delete any files at all, but just check if they have correct data

PS thank you for the best torrent client

This was a bug which has been fixed in the 2.2.3 release