I'm using Excel 2003 Prof Ed. and am experiencing a similar problem as
described in previous posts, but can't find a solution. The formula works in
some cells but not in others. I have tried changing the format of the cell
and checking the formula, but excel does not even want to evaluate it, giving
the error mentioned in the subject above.

If I copy a cell that has a working formula (it displays the result), and
paste it, it's fine. Then when I edit the cell to change the criteria (e.g.
the range) then it suddenly stops evaluating and only displays the formula.
In fact, even if I only click on the cell and hit ENTER, it encounters the
same error.

btw. the formula is simple: =COUNTIF(B88:H97,"MT")

Please advise. Thanks.