I don't think anyone knows.
Sometimes, you can delete the old commandbutton and replace it with a new
commandbutton (and change the name so the macro will still work!).
Personally, I've never seen this happen. But lots of people have.
I like to use buttons from the Forms toolbar with the macros located in a
General module -- and assigned to that forms button.
I very rarely use the commandbutton from the control toolbox toolbar.
