Comment 41 for bug 554514

Just to add to what has already been said - I have this same problem. I am using akonadi to link to a google calender and addressbook but not to my standard kde address book and calendar (I was but stopped because of the problems I was having every time I started up my computer).
I can confirm that if I stop anything and everything related to Kontact, stop Akonadi, start Akonadi, start Koantact all works as expected. But if I let things happen as normal Akonadi complains of no resource agents.
If I stop Kontact and Akonadi and then start Kontact I get the error as well (which I how I generated the selftest attached)