top menu bar missing in Monterey 12.2.1

Running Monterey 12.2.1 on a 2017 MacBook Pro (13) and the top menu bar keeps disappearing. It appears if I re-start the computer, but inevitably--usually a few hours later-or after awakening from sleep-it won't drop down when I move my mouse to the top of the screen. Haven't changed any settings or done anything that might change the display area, etc., so I have no idea what's going on. Any ideas?