Over at answers.microsoft.com there's a long thread where Athlon CPU users are experiencing issues with the Meltdown/Spectre patch. KB4056892 appears to prevent a boot of the system after the patch is installed. In some instances a complete reinstall fixes the issue, but the update will once again push out and you're back where you started. Beware Athlon users. I have older AMD Athlon 64 X2 6000+, Asus MB, after installation of KB4056892 the system doesn't boot, it only shows the Windows logo without animation and nothing more. After several failed boots it do roll-back then it shows error 0x800f0845. Unfortunately, it seems it's not easy to disable the automatic updates without gpedit tweaks, so it tries installing and rolling-back the update over and over.