CalendarAgent keeps asking for access to "login" after reboot
What I would do in this situation is rename the "login" keychain in ~/Library/Keychains to something like login.keychain.old.

Then I would open the Keychain Access app and drag login.keychain.old into the keychains sidebar. OS X will create a new login keychain. So all you have to do is open the old login keychain list you created and drag the passwords into the new login keychain. 

Hope this helps.