When attempting to run Windows Update on a Vista SP2 machine I get "Code 80072EFE" and updating fails. Appears any connection to a Microsoft update server is thwarted (even informational queries). All other web/browser behavior seems normal. Using Avast Free 5.0, with the Vista Firewall on. Have installed new Windows Update agent. No improvement. Oddly enough, based on a tip from this site I tried
This resulted in success (updating worked). However, following a restart, updating fails again and dns trick does not help.