Röviden: A torrent fájl dat fájlja sérült, törölni kell az utolsó pár torrentek közül a hibás torrent fájljait.
in my case I've got the same problem newly, the problem is a miscalculation of a torrent file data since the utorrent allocates space for that file it needs its information and its downloaded parts and left parts ...
all that is saved in a dat file inside the torrent folder (which contained an error) unfortunately I had to loose my progress in the download to solve this issue i had to delete the dat file in order to make utorrent analyze the available data and create a new one but it couldn't just do that and kept hanging (not responding and rewinding everything done in the ui window (like stopping, deleting, changing .. ) so i had to delete the torrent with the data and torrent file (remove and delete data + torrent ) restart utorrent and add the torrent again and start over ..
it should be a newly added torrent, another way to locate that torrent is to do a force re-check for them one by one and the corrupted one will force the app to hang and not response ..
I hope this may help ..