Going with what Dave said, if your cursor resides on the last row or below
when you start the macro, and you have something like iRow =
ActiveCell.End(xlDown).Row, you are sending the execution to the bottom with
Cells(irow + 2, 5).FormulaR1C1 = "=R[-1]C*R[-2]C3"
You would have to make sure your cursor has some rows with data in them
beneath it to avoid the problem and can do that by adding

Range("A1").Activate

as the first command in the macro.

" wrote:

I have a macro that contains the line:

..Cells(irow + 2, 5).FormulaR1C1 = "=R[-1]C*R[-2]C3"

The first time a worksheet is created and the above code is executed
when irow=15, the formula produced in E17 is "=A65536*$C65535". If
I run it again, the code executes properly and cell E17 gets the
formula "E16*$C$15". Does anyone have any ideas? I've exhausted all
mine, and have concluded it's an Excel bug.