kurz mal für Dich Google bemüht

Eines der beiden Wege sollte helfen:

ok i have lion like the last poster and here is how i fixed my sharing problem. i went in system preferences to users. from there i made sure it was unlocked to make changes. i then clicked guest which had on. i then unchecked the bottom box allowing computers to connect to shared folders. then it went away

oder dieser hier:

There is an outside chance you may have enabled that computer to automatically log on when you start up. Go to system preferences and hit Accounts. Click on your account and unlock it if necessary. If the offending server is listed highlight it and click the minus sign at the bottom and it will never return.