stuck at a plateau

when you find your learning stuck at a plateau, how do you progress?  I play a computer game per day  or problems (Millenium Chess Pro), read the classics, work on chess.com Tactics, Openings etc.   Is it just a matter of keeping at it?  Hiring a teacher? Stop exclusively playing the almighty computer? Join a Chess Club? (I'm not that good yet).

You're pretty much doing all that you can, improvement takes time, don't expect results overnight. You could try getting a teacher like you mentioned... I do online lessons using Skype video calls and a live online analysis board, the first lesson I give is free, and after that I'm pretty cheap, only $20 for an hour lesson, I know most coaches are a lot more than that. Message me if your interested. 

Possibly of interest:
Simple Attacking Plans by Fred Wilson (2012)
https://web.archive.org/web/20140708090402/http://www.chesscafe.com/text/review874.pdf
http://dev.jeremysilman.com/shop/pc/Simple-Attacking-Plans-77p3731.htm
Logical Chess: Move by Move by Irving Chernev (1957)
https://web.archive.org/web/20140708104437/http://www.chesscafe.com/text/logichess.pdf
The Most Instructive Games of Chess Ever Played by Irving Chernev (1965)
https://chessbookreviews.wordpress.com/tag/most-instructive-games-of-chess-ever-played/
Winning Chess by Irving Chernev and Fred Reinfeld (1949)
https://web.archive.org/web/20140708093415/http://www.chesscafe.com/text/review919.pdf
Back to Basics: Tactics by Dan Heisman (2007)
https://web.archive.org/web/20140708233537/http://www.chesscafe.com/text/review585.pdf
https://www.chess.com/article/view/book-review-back-to-basics-tactics
Discovering Chess Openings by GM John Emms (2006)
https://web.archive.org/web/20140627114655/http://www.chesscafe.com/text/hansen91.pdf
Openings for Amateurs by Pete Tamburro (2014)
http://kenilworthian.blogspot.com/2014/05/review-of-pete-tamburros-openings-for.html
https://chessbookreviews.wordpress.com/tag/openings-for-amateurs/
https://www.mongoosepress.com/catalog/excerpts/openings_amateurs.pdf
Chess Endgames for Kids by Karsten Müller (2015)
https://chessbookreviews.wordpress.com/tag/chess-endgames-for-kids/
http://www.gambitbooks.com/pdfs/Chess_Endgames_for_Kids.pdf
A Guide to Chess Improvement by Dan Heisman (2010)
https://web.archive.org/web/20140708105628/http://www.chesscafe.com/text/review781.pdf
Studying Chess Made Easy by Andrew Soltis
https://web.archive.org/web/20140708090448/http://www.chesscafe.com/text/review750.pdf
Seirawan stuff:
http://seagaard.dk/review/eng/bo_beginner/ev_winning_chess.asp?KATID=BO&ID=BO-Beginner
https://web.archive.org/web/20140708092617/http://www.chesscafe.com/text/review560.pdf
https://www.chess.com/article/view/book-review-winning-chess-endings
https://web.archive.org/web/20140627132508/http://www.chesscafe.com/text/hansen173.pdf
http://www.nystar.com/tamarkin/review1.htm

Analyse Your games on chess.com and see where you make mistakes. We all make errors but where do you make mistakes the most. The endgame, middle game, or opening. Figure it out and then learn that part of the game.

I wish I was stuck at a plateau.  I'm currently stuck in a very steep valley. ;-P

you could hire someone, I am giving a free lesson if you want, just message me, and why to play against a computer? is fun against a human, against a computer not so much, play against humans

It's normal to reach a plateau, which normally results from one of two causes: you have reached the limit of your chess knowledge or there are errors in your thought process. Do you analyze your games? Doing so will be very helpful in deciding how to climb farther. It's good that you are doing some study, but figuring out what you are lacking in your games might point you towards other aspects of the game to study.

I wish you the best in finding further improvement.

Tactics and more tactics. 

Very few people know this secret which is that Hikaru Nakamura stays sharp using the tactics trainer on chess.com.