The most recent January Windows Update is broken on a number of PCs, but at least virtual machines don't seem to be impacted.

As reported by Windows Latest, Microsoft has updated users in a support document that it is "investigating customer reports ...

Microsoft is investigating reports that some Windows 11 devices are failing to boot with "UNMOUNTABLE_BOOT_VOLUME" errors ...

Several users on Reddit running the 9800X3D chip on an Asus motherboard reported that their desktops suddenly failed to boot up.