If you've recently changed your Yahoo! Account password online and have Yahoo! Messenger set to automatically save your Yahoo! ID and password, Yahoo! Messenger won't automatically obtain the updated password change information. So, if you have it set this way, you'll need re-set Yahoo! Messenger by manually entering your Yahoo! ID and the new password. Here's how:

1. On the main Yahoo! Messenger window, select your Yahoo! ID in the "Yahoo! ID" field and press Delete on your keyboard.
2. Re-enter your Yahoo! ID in the "Yahoo! ID" field.
3. Select your old password in the "Password" field and press Delete on your keyboard.
4. Enter your new password in the "Password" field.
5. Click Sign In.