During normal operation (i.e. adding, deleting, editing and sorting To-Do items by priority) the To-Do list gets slowly corrupted, i.e. wrong items are deleted, I'm getting duplicate items, etc.
An example how to reproduce this bug: starting with empty list create a new To-Do (let's call it A), then create another one (B), delete A, and create yet another one (C). You should have B and C in the list. If you now click 'purge completed', you'll get twice the C.
Please address this bug with the current maintainer of KOrganizer; we do not maintain that software package. Use the KDE bugtracking system.
I did report it to KDE.org and received reply that it has been fixed in the current relaease. Would be nice to find the RPM of the corrected korganizer in updates or in rawhide if possible.