A family of Microsoft spreadsheet software with tools for analyzing, charting, and communicating data.
Which platform you're using doesn't matter - circular references work the same in both Win and Mac XL.
You don't give a lot of information here... does this happen in every workbook?
If not, what is the formula that gives you the circular reference, and what cell is it entered in?
Since cells that have values, rather than formulas, cannot cause a circular reference, if this only happens when you enter a negative number, I'd look for a IF() formula that only calculates one of the results if the test values is negative. For instance, if you enter this formula in cell A1
=IF(B1 < 0, A1 + 2, A2 - 3)
XL won't give you an error as long as B1 >= 0, because it will only calculate the second (false) term, A2 - 3. But if B1 becomes < 0, XL will try to calculate the first term, A1 + 2, and won't be able to because it references the same cell as the one the formula is in.