After uprading ktorrent from 3 to 4 version i've found that DC++ application rehash files in share with no any objective reason. Rehashed files was seeded by KTorrent, so i've checked, why it is happening, because files have been downloaded long time ago and shouldn't change. Hashes remain same, but mtime of files some time changes to current system value.
I think the reason is that KTorrent sometimes opens file for uploading in write mode that lead to updating of file modification time.
KTorrent 4.0.0 (from sources with disabled media player plugin), KDE 4.4.3, Debian SID.

This is due to a bug which will be fixed in 4.0.1

George wrote:This is due to a bug which will be fixed in 4.0.1

It sounds good. Thanks.

I've installed new (4.0.1) version and used it for two days.
The problem still exist. MTime of some files have been updated.

Seeding doesn't lead to the modification time being updated here.

I've reinstalled KTorrent from SID repository (now it is 4.0.1) and the problem has gone.