This is for an Intel-based MacBook running OS X 10.5.8 Leopard.
When I open Mail, it prompts for the keychain password with the below message:
Mail wants to use the “login” keychain.
Please enter the keychain password.
When I enter the correct password repeated times, it gives this message every time:
Sorry, you entered an invalid password.
Please try again.
I even changed the password in System Preferences and tried the new password with the keychain message that appears in Mail, but the same thing keeps happening. The Caps Lock key is off.