Odd technical glitch this morning.
I use a lot of USB devices, and have a powered USB router. Rarely, it won't "boot" when I turn the surge suppressor power switch for my computer stuff on in the morning. Since my USB keyboard is powered by the router, that means the computer won't boot, instead posting an error message. However, the default is a Bluetooth keyboard, and that's what the computer complains is missing.
This happens rarely enough - maybe once a year - that it takes me a while to realize what is going on. (Especially first thing in the morning. ;-)
The cure is to unplug and replug the USB router, then restart the computer.