Q: I have an Unknown Device with hardware ID ACPI\MSFT9002 in device manager. What is this?

 

A: If you have the OS of Win 7 installed on your machine the OS may be selected incorrectly in BIOS.

1. Please reset and go into BIOS
2. Go to the Main Tab and change the OS Select from Win 8.1 to Win 7
3. Exit and Save Changes

After windows load back the unknown device will be gone.