I don't believe this is exclusive a nVidia card issue, it just happens to to apply here.
Running W7 Pro x64, I do have those two SHA-2' KB patches installed, but when I try to install nVidia drivers using DM (no need for that bloated Ctl Panel and all the fluff), the installation goes fine, but on re-boot, DM has a yellow flag with a Driver signing error.
I did some research with 3 methods to disable driver signing, but 2 of the three didn't work (Command Prompt & Group Policy). The 3rd has to do with using WinRE which I've never done before (or had to). This involves forcing power off re-boots 3 times.
I also have read that holding F8 during booting does the same thing (I believe).
Anyone have any input of this??