Really REALLY Weird Frozen Keyboard Issue!

All of a sudden, my iMac developed this REALLY weird keyboard problem that is driving me NUTS. I am typing something in ie. macos "Notes", and then all of sudden, BAM! My keyboard makes like it hit a brick wall, and won't type ANY character. No numbers, no letters, no RETURN key, no SPACEBAR.

n.b. I'm on High Sierra, but I have NEVER encountered a problem like this one before, on any macos, including Sierra/High Sierra.

Q. So all keys are frozen, when keypresses don't register?

A. No! That's also weird.... Some keys like the Printer key still function!!

Q. Keypresses don't work in "Notes" app only or all apps?

A. When it freezes in "Notes", I then try typing in TextEdit, TextWrangler, or a browser, and still no characters appear! (However, while frozen in Notes app, it may work immediately afterward in TextWrangler. But I have seen this same 'freeze' occur after a short time in TextWrangler. Moreover, sometimes it will be frozen in my browser, but work in TextWrangler!).

Q. So the keyboard freezes up in all apps?

A. No! It works fine in "Stickies" app! It is the only app I've found where the keyboard always works, even while still frozen when I switch to "Notes" or "TextEdit", etc!

Q. Install any new software?

A. I made no changes to my macos recently, no new software, no new nothing. I thought; "Is it a keylogger??" -- but it can't be. Because it ALWAYS works fine in Stickies!

Q. Does rebooting solve the issue?

A. I logged out of my session, then it started working again, then it came back! I restarted the computer, it started working again, then it came back! It's just not going away!

Q. Is this issue permanent?

A. No. That's the weird part. It somehow, at some point, resolves itself without my having to do anything, including not needing to log out of the session. But then after typing a bit, it starts back up again, where the keyboard (almost) freezes! Sometimes it'll stop typing again after a sentence and a half!

Q. Does plugging the keyboard into another USB port resolve the issue?

A. I wish.....

Q. Is it the keyboard itself?

A. No. I tried other keyboards, same deal! Also, since some keys like Printer work, and since it is intermittent but somewhat predictable, that too leaves the keyboard off the hook.

Q. Did I catch a virus; ie. keylogger?

A. Not likely. For then, the same behaviour would show in the "Stickies" app.

Q. Have you checked the settings for Accessibility and Keyboard?

A. Yes. I checked everything in those two Preference settings. It's all at default, there is no "Sticky" or "Slow" keys set, or anything turned on.

Q. Can you type in this Apple Discussions text box?

A. Yes, I find for now I can type fine here. But if I go back to "Notes", I cannot! Or, if I try to type something in the address bar of the browser I am in, it is frozen! (No key entry is allowed). But, if I type this something in the Google search page of this same browser, no problemo! :(

Q. Have you travelled recently to Hel**? With your Mac?

A. No.

Wait.... Does Florida count?