The problem I was having with the desktop/finder was NOT as I presumed.
Another issue developed. I still could press COMMAND and left-click the mouse to highlight individual items when, for example, wanting to move several of these to the trash at one time. However, if I inadvertently clicked a file and then did not want to move it with the batch, I could not simply command/click to un-highlight that one item. I had to un-highlight all the items by clicking on an empty space on the desktop and start over with the highlighting.
So . . . I discovered that the MM2 was malfunctioning. I replaced it with an identical (working) model of the MM2 and all functions like it originally did as far as re-naming/highlighting files on the desktop is concerned (i.e. left-click to highlight, then type for changes to text).
Yippee!
