One of the most annoying things that can happen when you start up you Mac is to be prompted repeatedly for a keychain password for various applications. This sometimes happens after you have changed your login password. To make matters worse the password that these applications request is the previous one and not the most recent password.
The solution to this problem can be found on Apple’s support website. It requires you to delete a folder in the location ~/Library/Keychains/ which has a long alphanumeric name. After you have deleted this folder you should restart your Mac immediately. This should prevent the problem from reoccuring on subsequent logins.