I had the same issue. It was indeed due to a new RSS feed had added with an embedded control character. The gui was effectively hung up so I couldn't fix it that way. I couldn't find anything I could do to the server and hand editing the rss.dat file was unsuccessful. So to repair the damage without having to reenter all the flters and paths again I just copied the rss.dat to a windows utorrent directory(in my case running under wine), deleted the bad feed via utorrent, and copied the repaired rss.dat back to the utserver directory. I hope it is as easy for you.