I have noticed that ktorrent does not run properly after upgrading from Fedora 12. I suspected the reason is in some misconfiguration because of config files incompatibilities. The solution below is fairly simple.
mv ~/.kde/share/config/ktorrentrc ~/.kde/share/config/ktorrentrc.bak
Edit all sections with plugins and change all “enabled” to false, save and restart ktorrent. You can experiment with enabling them one by one to find which of them crashes ktorrent.