iMac High Sierra Upgrade - USB Keyboard not recognized
I updated my Late 2013 27" iMac to High Sierra (from Sierra) last night. When the install finished, My Apple USB wired keyboard (with number pad) didn't appear to be recognized. I tried unplugging the device and plugging it into a different USB port with no success. The keyboard had been working just fine under Sierra. I rebooted the machine with the same results. The keyboard does work on another iMac of the same vintage (but running Sierra). Can anyone point me to a fix for this situation? I have no other devices plugged into the USB ports. My Bluetooth Magic Mouse works fine, but I prefer the wired keyboard with the number pad.
iMac (27-inch, Late 2013), OS X El Capitan (10.11.1)