When you click “Shut Down” on your Windows 10 PC, Windows doesn’t fully shut down. It hibernates the kernel, saving its state so it can boot faster. If you’re experiencing computer problems and need to reset that state, you’ll need to restart your PC instead.
We’ve personally experienced this problem ourselves. When faced with weird system problems that may be caused by a buggy driver or other low-level software issues, the problem persisted after shutting down our PC and booting it back up.
This weirdness is all thanks to Windows 10’s “Fast Startup” feature, which is enabled by default. This feature was introduced in Windows 8, and has also been called Fast Boot and Hybrid Boot or Hybrid Shutdown.
In the traditional shutdown process, Windows fully shuts down everything, discards the running system state, and starts up from scratch the next time the PC boots. When you hibernate, Windows saves the entire system state, including all your open programs and files, to disk so you can quickly resume from where you left off.
Fast Startup mixes the traditional shutdown process with hibernation. With Fast Startup enabled, Windows 10 discards all your open programs and files (as it would during a traditional shutdown), but saves the state of the Windows kernel to disk (as it would during hibernation). The next time you boot your PC, Windows restores the kernel and starts up the rest of the system.
The kernel is the low-level core program at the heart of the operating system. It has full control over your computer and is one of the first things loaded during the boot process. The hardware drivers that your computer uses to interact with its hardware devices are part of the kernel. Loading a snapshot of the kernel speeds up the startup process, as Windows doesn’t have to take time to load all the device drivers and reinitialize your hardware devices.
This kernel hibernation process all happens automatically when you click “Shut Down,” and people will rarely notice the difference. But it means that if a hardware driver in your kernel is stuck in a weird state, shutting down your PC and then booting it back up again won’t fix the problem. Windows saves the current state and restores it instead of re-initializing everything.