text: The most common cause for this issue is you've logged on another computer. When you log in from different computer, Yahoo! will disconnect the session from your first computer... then once you've connected, your first computer attempts to re-connect to Yahoo which will cause you to disconnect. \n\nTo solve this problem, simply Log Out/Log Off from your Yahoo when you've finished using a computer.\n\nAnother possible cause is someone KNOWS your Yahoo! ID and password. in this case, things become ugly. Immediately change your password or be prepared for losing your account.