[jameszhang]

My browser (Chrome) shares screen real estate between its search functionality and address bar. Therefore, if I have searched "facebook" on Google but have not explicitly typed "http://facebook.com" into the address bar, Chrome remembers the "facebook" search as I start to type it out. As a user, the next most obvious action to take is to tab-complete + enter, and voila, there goes the Google search for "facebook".

[nawitus]

When I tab-complete + enter, Firefox autocompletes it to http://www.facebook.com and then opens the URL.

[jameszhang]

Have you explicitly entered http://www.facebook.com into the address bar in the past by any chance?