If your using the Ethernet Index number there a good chance it will change. Just depends on how much you much you manipulate the installed devices. Uninstalling it or re-installing it are good ways to force a index number change. I think some driver updates monkey with it as well. I recently found my self fighting with windows over what type of network connection it was, and during the process something I did in moving it from public to domain or private caused the index number to change again.