Thanks for your help. Upon further investigation, after a long process of
elimination, I discovered that the reason Excel stopped sorting the
spreadsheet properly was because I had added data to columns Y and Z without
putting a heading name in the header. This ended up confusing Excel. Once I
added names to my new columns, Excel once again behaved as it should. Thanks
again.
Sally

"Dave O" wrote:

Apparently, the Header box is automatically checked when the first cell
in the highlighted range contains a border along the bottom edge.

Ideas for a work-around:
~ don't highlight the column header
~ record a macro that includes de-selecting the header, and run that
instead of manually sorting

Maybe? Some help, perhaps?