I had a similar problem after a password changed, and this sorted it out. You may find that it works for you as well.
If you want your default keychain to be unlocked automatically when you log in, synchronize your Keychain Access and account login passwords by doing this:
- Open Keychain Access (you can get to it by choosing Utilities from the Go menu in the Finder).
- From the Edit menu, choose Change Password for Keychain "login."
- Type the former password of the account that you are currently logged in to, then click OK.
- If you entered the correct password, a new window appears; enter the original password again in the Current Password field.
- In the New Password field, type the password that matches your current account password.
- Re-enter the newer password in the Verify field, then click OK.