Author:IE guy
Subject:Internet Explorer config
Category:Web Booster
Message: "Internet Explorer must consider the requested URL to be on the intranet (local). If the computer name portion of the requested URL contains periods (such as and, Internet Explorer assumes that the requested address exists on the Internet and does not pass any credentials automatically. Addresses without periods (such as http://webserver) are considered to be on the intranet (local); Internet Explorer passes credentials automatically. The only exception is addresses included in the Intranet zone in Internet Explorer."

SSO giving password prompt in IE 6   Vince 10.Dec.04
    Internet Explorer config   IE guy 12.Dec.04