People have been asking why, all of a sudden, they can’t go to a web site with Internet Explorer unless they type in the full address (with the “http” in front) — when normally they could just just type www.whateverdomainname.com and IE would put in the “http” part.
This is one of the most commonly reported problems caused by the update referenced in Microsoft security bulletin MS06-015.
There’s a registry edit that will fix it; you’ll find instructions here, along with a list of the various problems the patch causes.
Also, Microsoft has re-released the patch that is causing these problems. It’s been completely re-engineered; the new update should be installed automatically if your system is set to use the automatic update service. You can read more here.