Windows 2000 Pro/ Office 2000 Pro

I have a Worksheet that has 1671 rows of data and formulas at the bottom of
several columns.

Column "M" contains data values imported from another App and Columns G &
H contain the formulas =if($M1=0, $M1,0) and =if($M1<, $M1,0) respectively.

I have verified all cells within the relevant range have been formatted as
"Number" and even multiplied the values in column "M" by 1, as suggested in
the KB to ensure they were converted to numbers and did not come over as text.

While working in the file yesterday, I sorted the data and the "Sums" for
all =Sum ()formulas changed! I recopied the formulas in columns G & H and
then resorted with the same result (actually, different results = the totals
changed again!)

The totals are not consistent with the sort. For example If I sort by
column A I get one total, I sort by Column B I get a different total, If I go
back and sort by column A again, I get a completely different total.

I have never run into this before and I have no idea what else to check..

Any suggestions?

I checked several other worksheets and workbooks and they do not appear to
have this problem

TIA

BAC