WSUS server itself failed to get updates

Symptoms:
- System Event ID 16 with Source=Windows Update Agent and Category=Software Sync
- Error 'PT: Cannot recover from fault' on WindowsUpdate.log

Solution:
In Internet Options, add 'http://' to Trusted sites (or Local intranet?)
Remember to use server name in both Internet Options and Group Policy instead of 'http://127.0.01' or 'http://localhost'