I also had problems with kontact and ktimetracker although all is working now on KDE-4.8.2. My error message was different to that which you reported. http://www.linuxquestions.org/questi...ml#post4656338
In KDE, check under System Settings->Personal Information->Akonadi Resources Configuration that akonadi can find appropriate files for the Personal Calendar and Personal Contacts.
At the time, I was also struggling with getting kmail to work, and ended up deleting my ~/.kde directory and rebuilding from scratch.