I changed a number of calendars two days ago. Since then I get a notification like "...ics file ... as changed on disk. As a precaution, a backup of its previous contents has been created at ... " This has been running from the time that I start korganiser until I shut down (and in fact, my machine won't shut down, so I have to do a hard switch off.) I do not know how to disable this / stop it - I do not need the backup since the data was imported in the first place. I switched from ubuntu 12.04 to kubuntu 12.04 about a month ago because I could not stand the way Unity works. I tried kubuntu a number of years ago and liked korganiser, so I also moved from thunderbird to korganiser.
I deleted the calendars and that stopped this problem.