Version:           GIT (master) (using KDE 4.7.0) 
OS:                Linux

[App version is really 4.7 trunk, but the menu doesn't list that.]

I can apply changes to my tasks and events in an ICAL source and they will be remembered after a reboot. I can also add tasks and events with no problem. But I cannot delete anything. Korganizer can be restarted and it will remember the deletion, but when I reboot my system and start up KOrganizer, the deleted event is back! 

This might have been a problem that arose with the migration from 4.4 to 4.6, but has been around ever since. I believe this is the case because I never had the problem in 4.4, and in 4.6, old tasks long deleted were suddenly making a comeback. 

This behavior does not occur with an ICS file. 

Reproducible: Always

Steps to Reproduce:
Try to delete a task or event from an ICAL source. Quit KOrganizer. Start KOrganizer. It is gone. Now reboot your machine. The task/event is back. 

Actual Results:  
See above

Expected Results:  
See above

It is also interesting that the ICAL resource remembers when I change the date or reminders of a task, but it will NOT remember that I checked the task as completed. It's crazy and driving me nuts. 

I had opened a thread in the forums that didn't yield any results: http://forum.kde.org/viewtopic.php?f=20&t=95804

I have also remigrated to akonadi twice (once in 4.6 and then again in 4.7). No success!

(I am marking this as a data-loss causing bug because it does lose data - even though I am not losing data I want, but to the opposite, having data come back that I wanted gone. If you disagree with that classification, I at least wanted to point out why I classified it as that.)