Few weeks ago, I have installed KDE and after restarting and changing the session I get an error message "Could not start kstartconfig. Check your installation" and takes me back to the login screen. Back to the Gnome session, I have tried few from usual Gsearch but nothing worked. Here is a temporary solution.
- Create a new user (System->Administration->Users and Groups)
- Feel free to add user privileges according to your needs.
- Log out and login to KDE session with the new user name and password.
- Happy happy KDE.