If you've recently changed your network password, you may begin receiving "Keychain Access wants to use the 'Login' keychain..." dialog boxes frequently while using your Mac:
Fortunately, fixing this is simple.
1. First, navigate to your Utilities folder on your Mac, and open the Keychain Access application.
2. Next, choose Edit > Change Password for Keychain "login"...
3. In Current Password, enter your old password (hint: This would be a password you recently used to log into your Mac), then the password you recently chose as your new network password. If you enter the wrong current password, don't worry: keep trying previous passwords until it accepts it.
4. Click OK.