1) You can't start  a new macro when a previous one is running, unless
perhaps if that macro keeps itself active using a timed interrupt. I.e.
there's no point in trying to do this.

2) If the user  chooses "disable" then you're not running  macros, so you
can't take any actions at all. However, you could hide all the other sheets
before saving the workbook. Then, if you disable  macros, that's the one
that will be seen. And if you enable  macros, you can use the auto-open
event to un-hide the other sheets. You can also use the before-save event
to hide the sheets  again before the save.