We have several Lenovo X220T with Windows 8 x64 which are occasionally causing
DRIVER_POWER_STATE_FAILURE (0x0000009f) bugcheck/bluescreens. The systems are using OEM drivers for most everything and the issue does not seem to be related to any one individual use case.
Upon shutdown, the system hangs at the "Shutting Down" spinner. Plugging in or removing any device does not cause an appropriate plug event to occur on the machine, and the device is not usable.