Disappearing Curser (not the mouse pointer)

This isn't a Logic question, but this is my community for help on all things Mac... So with apologies for asking a Non Logic question, please help if you can.

I’m having the weirdest issue. The disappearing curser. (NOT the pointer arrow) The curser in a document. Or, if there's not a curser, the "focus" of the computer seems to go off the current document and won't accept information. (If I try to input without clicking on the document, I get the error sound)

This happens on many different softwares. (Mail, Logic, Safari)

I’ll try to explain.

For example, right now I’m writing this post. Every minute or two, the curser will just disappear and this document is not “active” or accepting information. I don’t know where the curser/focus is going. But if I click back on the post (or whatever it is I’m working on) I can continue until, it just happens again.

I noticed that, right at the moment the curser disappears, the “Terminal” appears. If I quit terminal, and continue, the pattern will happen again. The curser “goes elsewhere” and I have to click on the document again to input information and terminal boots up again.

I thought maybe it was a hardware issue, like mouse malfunction. So I unplugged the mouse and keyboard.. but same thing happens.

PLEASE... this is a real drag and any help is appreciated.

i assume you mean the cursor... that is odd, and sounds like something's damaged in the OS. you could try installing the HS combo installer (it will overwrite the OS); of course, backup first (just to be safe)

https://support.apple.com/kb/DL1970?locale=en_US