I am getting the same thing since April 12th as well when I try to download updates.
It's only on Windows 7 machines though, as I have another that runs Windows 8.1 and that one
checks, downloaded and installed new updates fine on April 13th.
In order to stop the CPU from running at 25% all day long, I located Windows Update Service
(in task manager on the Services tab....press the services button and scroll down to "Windows Update"
and I first stopped it from running and then disabled it) machine went back to 1-5% CPU like normal when not running any applications.
I hope they fix it soon because I don't like to have this feature disabled.
I have to re-enable it once a day to update MSE virus/malware definitions and then re-disable it to save my CPU processor from running 25% all day long.