I had created an array using the frequency function. I tried to delete the
last cell in my array. Alas, what a mistake. I got stuck with an error
message that explained to me that changing an array was not acceptable.
However, the undo function would not let me replace it with what I had.
Excel locked up and whatever I clicked on just repeated the array error
mistake.

I had to use task manager to exit Excel and lost all that I had not
previously saved. Was there some other option to exit from an error message?