How to Fix Pop-Up Yahoo Messenger and Lock the Computer

Yahoo Mail has a built-in Chat, so when you access your mail, you maybe automatically signed in to that chat option. be OFFLINE from Mail chat so you will remain online the Messenger downloaded version.

Cause,

You cannot be simultaneously signed in to more than one Messenger interface with the same Yahoo! ID.

Resolution

For steps on how to disable the Messenger Chat feature in Yahoo! Mail

How to check if you have Messenger set correctly on your computer:

Select the Messenger menu | select Preferences.
Select the General category.
Uncheck the check box for Always sign into my mobile phone when I sign out of Messenger, if it is not already cleared.

If you use a third party messenger service you will need to follow their instructions on how to verify this setting.

NOTE: If you suspect that an individual or device has logged into your account without your consent, please make sure to change your account password.

Additional Information

To be signed in to different Messenger interfaces with the same Yahoo! ID please you will need to use Yahoo! Messenger 11. To learn more about our new Multiple Points of Presence capabilities in Messenger 11, click here.