I am summing a column of numbers, but data from several cells are not adding
to the sum. This is a basic function and a potentially serious bug, but I do
not know how to report it.

I found this problem when I was checking for errors after modifying a data
list. After deleting extraneous data, I wanted to check a column of numbers
to be sure it matched the unmodified column. I totalled both columns by
using the "=Sum(XX:YY)" function; the totals were off by 4.

I had not sorted the list, so I copied the modified column beside the
original and subtracted one row from the other in each column: equal numbers
result in zero, showing the discrepancies. These formualas showed zero for
every row. Yet, summing the columns resulted in different totals!

I identified several cells which were not being summed in the original
column of numbers. The autosum button usually sums an uninterrupted list of
numbers in the column above it. But, using autosum at the bottom of the
problem column put in a sum function which stopped at the problem cell,
apparently reading that cell as a blank although it contained a number. If I
click on the cell, delete its number, re-type and re-enter it, the cell is
then added in by the sum function at the bottom of the column.

I would like to send a sample worksheet to Microsoft so they could possibly
tell me what may be happening. Is there a way to report this?