Lawrence, I have been following this topic with great interest.
I have a client I have only just begun managing with a server running SBS2008 SP2, and WSUS 3.0, also reporting Event ID 13042. WSUS is set up on 8530. While Sharepoint is installed, it is not located under the Default website.
I have checked to make sure SSL is off for the Default Website, and that anonymous authentication is enabled per all of the KBs. The SelfUpdate virtual directory is present on the Default Website, points to the appropriate location, and has all of the appropriate security permissions.
The server can update clients just fine, but it cannot update itself, and I have no idea what could be going wrong. Any insights would be greatly appreciated.
Everyone gets everything he wants. Me, I wanted to be a sysadmin. And for my sins --they made me one.