I have the same problem for Update for Microsoft XML Core Services 4.0 Service Pack 2 (KB973688). Tried to install it manually, but the file is not located in the System 32 as indicated. It's located in another Windows location. The manual download will install, but the update still shows "failed."
Frankly, I spent a day trying to find a solution; and now I just don't care anymore. Apparently you and I are not the only ones and I am assuming someday, someone will figure it out.