I got a message when I tried to unstall add-on which is developed on vs2003 with B1DE:
An exception occurred while unstalling. This exception will be ignored and the uninstall will continue. However, the application might not be fully uninstalled after the uninstall is complete. --> Object reference not set ro an instance of an object.
Maybe it is not right way to unstall add-on through "Add/Remove Programs"?