On Vista user can't update. We need to fix this issue ASAP. Here are the steps to reproduce. The problem is only seen with Vista.

1.) Make sure UAC is Disabled and user logged in as Admin

2.) Install 1.4.2_20 JRE

3.) Create the UpdateServletURL as sepcified in page below.
http://webeng-dev.sfbay.sun.com/internal/internal_release/javaclient_update_setup.html

Make sure you are connected to internet and can acess sun.com site.

4.) Now launch JCP (Java Control Panel) and goto update tab.

5.) Clcik on "Update Now" button.

Actual Behavior:
Errro dialog shown which is quite irrelevant as User can access the internet. For more info check the attached image. I got the simillar result wit UAC enabled as well.
Expected Behavior:
User should be able to update to 1.6.0_13.