I wish I could help but I don't think I can. I finally called MS Support and the person got into my machine and did a "manual download" of the updates. Then she said the magic words: "Don't worry!" My blood ran cold when she said that, because that's when I started to worry.
When it was all done, my regular background showed up for less than a second...and the machine was locked again. I noticed the mouse worked on my RH screen but not the left--but just a moving arrow, nothing happened. So I pulled the HDMI off on the LH monitor and got the log on screen, but not the other way around. Finally I moved the DVI for the LH screen from the Nvidia card it was on to the one the other card (both have 2 ports). Then I had to mess with the display settings and reboot. It was fine. It also took the next round of updates with no problem.