https://www.cnet.com/news/microsoft-amd-spectre-meltdown-halt-chip-patches-pcs-unbootable-brick/

Microsoft is putting critical Windows updates on hold after learning that some computers can't start up again after installing the patches. 

The updates to Windows included fixes for the Spectre and Meltdown flaws that made a device's central processing unit vulnerable to hacking attacks. The PCs that couldn't reboot had processors made by AMD, one of the three chipmakers whose products were affected by Spectre.