I recently had this problem and found this link while searching for a solution:

http://searchengineland.com/070523-083042.php

To disable this feature, I needed to remove a factory installed application called "URL Assistant" which is different than the 2 solutions I found in the article and comments.

"URL assistant," eh? Sounds sinister enough. "Here, let me assist you with that naughty 404 URL, wouldn't want you to have to look at a page free of advertising, now would we?"

This sounds familiar ... almost like what Verisign tried to pull a couple of years back [c|net story from 2003], with the possible exception that the Verisign exploit worked for any computer (or other appliance) that used public DNS, whereas it appears that this works only for those computers that Dell and Google have "enabled."

-- rick