Problems "Mu4 #4

Chromebook/linux. I5. 8gig. mouse imput
In the score I am working, the more things I try to do the more faults I run into. I think in problem #2 I mentioned adding a new menu to the pallettes, grace notes. Now when I try to click 'n' key to enter notes.....
another new way for complete shut down. The program and system have been shut down and yet this problem now that it has started is just continuing! I hope hearing of these issues is helping someone to understand what is going on in the background.