IF you have AT&T internet service, you may encounter an annoying feature which you are automatically opt-in and you have to opt-out. For example, if you enter a domain name that doesn't exists, lets say: myexamplebhack.com you will get the att search results powered by yahoo.
At the bottom of the page, you will see a link that says: Why did I get this page? | Opt-out of this Service
Hope that helps.