Excel 2003 Sort Buttons Not Working Properly

We had an Excel 2003 spreadsheet that worked (and still does) correctly in regards to the Ascending and Descending sort buttons. That is, you click on row 1 of a column, click on the button, and it sorts the entire spreadsheet.

However, we had one of our employees make a copy of this spreadsheet and then make numerous changes to it. Now it will not sort properly. Instead of sorting all rows/column, it sorts only a block of the spreadsheet.

I did some research and found that Excel does an "implied" CTRL+A when you click on the Ascending or Descending button. I tried CTRL+A at various places in the spread sheet and sure enough, it's not selecting the entire spreadsheet.

I confirmed that there are no macros present. I have tried copying/pasting into a brand new spreadsheet. I even tried saving out to CSV and re-opening from the CSV. However, the problem persists.

Any ideas?

Thanks ChemistB. Just what I needed. Yes, basically it's going until it finds a rectangular block of blank rows, columns, or edge of the spreadsheet. Contradicts most other things I've seen that say it will select the entire spreadsheet.