[SOLVED] PC reboots instead of shutting down: Windows 11 update issue

I spent a long time chasing this one, so I'm posting the solution in case it helps someone else.

Symptoms

• On shutdown, the PC does not power off — it reboots instead. You can't hear the shutdown sound and the power LED stays on and the machine restarts.
• No blue screen is visible (the crash happens late in shutdown, after the display driver has unloaded).
• The problem does not happen in Safe Mode — there it shuts down normally.
• A fresh Windows install shuts down fine at first, then the problem appears after a few hours or days.
• Reinstalling Windows does not fix it permanently, and cloning the install carries the problem with it.

What it is NOT

• Not the RAM (Test passed 48/48, zero errors).
• Not a failing PSU or CPU (no component replacement needed).
• Not BIOS power settings (tried Power Supply Idle Control, disabling Global C-states, manual SoC voltage — no effect).
• Not "fast startup" or a wake-on-LAN setting.

The actual cause
The C:\Windows\Minidump folder contained several 0x124 (WHEA_UNCORRECTABLE_ERROR) crash dumps, all created at shutdown. Analyzing one in WinDbg with !analyze -v showed the machine check firing here:

nt!HalpPciReadMmConfigUlong
...
amdkmpfd+0x745e

The crash happens while amdkmpfd.sys (an AMD PCI filter driver) reads PCI configuration space during shutdown. On my system this old version of the driver triggers a fatal machine check. Windows labels 0x124 as a "memory" error, which is misleading — it's actually on the PCI/interconnect path, which is why MemTest passes and why Safe Mode (which doesn't load this driver) shuts down fine. The driver was installed automatically by Windows Update, not by me — which is why a clean install works until Update pushes it.

The fix
Find the driver's published name (run in an admin Command Prompt):

pnputil /enum-drivers

Look for the entry whose original name is amdkmpfd.inf and note its published name (mine was oem17.inf, AMD version http://20.50.0.0 dated 2020).

Then remove it:

pnputil /delete-driver oem17.inf /uninstall /force

Reboot. Windows falls back to its own Microsoft PCI driver and the machine shuts down normally again.

Important: because it came from Windows Update, it may be reinstalled automatically. Use Microsoft's "Show or hide updates" tool (wushowhide.diagcab) to hide the AMD driver update so it doesn't come back. If shutdown ever breaks again after an update, just repeat the pnputil steps.

Do NOT just disable the service with sc config amdkmpfd start= disabled — it's a boot-start driver, and disabling it (without removing the filter registration) leaves Windows unable to find the boot disk, resulting in a 0xc0000001 boot failure. Use pnputil /delete-driver as above instead.

My system, for reference: Ryzen 7 2700, Gigabyte X570 Aorus Elite (BIOS F40), Windows 11.