How come the XLA worksheet becomes visible?
 

I developed an Excel Addin in Office 2000. Testing it on an XP machine
running Office 2002 or 2003, if I remove the addin and then reinstall it
without closing Excel the addin.xla worksheet becomes visible to users! How
is this possible? What is going on and is there a way to stop it from being
visible?

Another problem I seem to get, is that doing this several times can end up
having several instances of the addin displayed in the Project Explorer.