Suse Linux 10.2
Ktorrent crashed while attempting adding torrent while disk was full.
Working now well in root mode. I have even downloaded incomplete torrents in root mode.
Ktorrent crashes and cannot be started in normal user mode.
I even tried uninstalling and reinstalling without any result.

Try running it from a terminal while in normal user mode and take the output of the terminal after the crash.

Sometimes crashes occur on messed up configuration of each program and even though you uninstall it the hidden folder stays on your home folder, it must be something like /home/USER/.ktorrent delete that also. To view them in KDE there is an option in konqueror on the toolbar saying View Hidden File And Folders, it will be a mess after that but you will find it.

Also as a last resort I would suggest you installing it from source, I solved my problems with ktorrent after this.

Wait...you wrote above, after your disk got full? Do you have different partitions for /home and / ?

Ktorrent can be started from terminal as su.

thanks vangelis for the tip.
I deleted temporary data and ktorrent is again fine