I have a sheet which calculates a loan amount which also includes a fee which
is a percentage of the loan amount, so I have iteration active to avoid the
circular reference error. To cover people who don't have iteration on there
is a macro which automatically turns it on when the sheet is opened.

The problem is that the formula gives diffrent results on different PC's. We
are all running the same version of excel (2003), but some have macro
security set to low, others to medium. Mine was set to medium and the result
differed from someone who had theirs set to low. I set mine to low and the
result changed to agree with the other PC (also set to low). When I reset
mine to medium the result did not change back, and now regardless of the
security setting gives the same result which is different from the what it
was originally showing. (I hope this makes sense!)

The difference is only one dollar, but for loan documentation it has to be
the same across the board. Can anyone suggest why this is happening? The only
other macro in the sheet is one that resets the input cells to their default
values. It doesn't modify any formulas.