My 13th Microsoft KB Released!
Inventory Tool for Microsoft Update unable to download the Update Catalog successfully
Microsoft Update Tool Sync Advertisement failed and unable to download the Update Catalog when you are using Proxy Server to access Internet. And you got the message ID 11456 in the Advertisement Status of Microsoft Update Tool Sync. Also, in WUSSyncXML.log, there are records like "User Account:NONE".
For the Solution, Please read: http://support.microsoft.com/kb/555926