It starts with the KDE's notifying applet. It pops up showing a non-existent "file operation finished" message, which repeats itself for countless times with a growing number of messages. At the end the desktop crashes. It is connected with kio_file and kdeinit4 in processes. I don't know what causes it, and how to get rid of it. It just happens without any visible file operations.
Any ideas?

Note: I'm not using anyone of Nepomuk or Akonadi or other stinking ***shits, yet I cannot get rid completely of those worthless annoyances.