I have a couple of issues that recently popped up.
If I click on a cell, and then click on another cell in the same workbook,
the original cell that I clicked on remains highlighted.

Also, if I open two spreadsheets that are not related, and highlight a range
of cells in one work book, then go to the second spreadsheet, I can see the
data from the first spreadsheet. The data is not entered into the second
spreadsheet. I've asked my help desk for help, and they don't know.