1. If you have a formula in those cells you can change it to look like this
=IF(A4=0,"",formula)
this will make the cell look empty, and make it's value equal to nothing.
2. If you have entered values in the cells you can use conditional
formatting and select "formula is" with the following formula
=$A$4=0
click the "format" button and change the font color to white (or whatever
you cell color is). Then click ok. This will make the cells look empty but
keep there value the same.
3. You could write a macro that would actually delete the cells every time
you enter 0 in A4. I can't help you here, but I know it's possible.
