Additional information:

This is Excel 2K and was recently upgraded. I also find that by copying a
worksheet containing a subtotal that was created on the old version, I can
now do subtotals on new data and get the groupings to work. Digging through
the Microsoft Support pages I found a tip (831824) about changing the
registry to get Excel 2000 functionality back on Excel 2002 and Excel 2003.
Could this be the "problem"? Am I the victim of a new "function"?