Trackpad on Macbook Air stops working

The trackpad on my 2014 MacBook Air spontaneously stops working. The mouse arrow won't move and clicking has no effect. A plugged-in mouse or use a Bluetooth Mouse will work, but the trackpad will remain ineffective.

Restarting doesn't make a difference. Resetting the PRAM (or whatever it's called these days) did nothing. Reinstalling the OS did nothing. Updating the OS (10.13.2) did not fix it. Completely shutting down and turning it back on did not fix it (plugged in or not plugged in). killAll Dock did nothing. Safe mode made no difference. Running Disk Utility did nothing.

I have noticed that after putting the laptop to sleep for a time, the trackpad will start working again (but not immediately). In fact, the length of time the trackpad will work before breaking down again is somehow proportional to how long it was sleeping.

*I do see the same message in the System Log occurring when the trackpad stops working:

hidd [HID] [MT] MTSimpleHIDManager :: handleNotifcationEvent device killed

kernel [HID] [MT] AppleMultitouchDevice :: checkBridgeStatusMessage Status: Reset

Any ideas?