Resetting your keychain in Mac OS X. The short answer is here:
To reset your keychain in Mac OS X 10.3 through 10.3.9:
- Open Keychain Access, which is in the Utilities folder within the Applications folder.
- From the Window menu, choose Keychain First Aid.
- Click Options…
- Click Reset My Keychain, which is under the General pane.
- Authenticate with your account login password.
- Quit Keychain Access.
- Restart your computer.