Hello and welcome to windrivers mvgood. In my experience Nero has always left something to be desired, either it will mess with audio encoding for no reason, disable the ability to read some file types, or in your case interfere with the cmd.exe file. There are several ways you can attempt to counteract a Nero issue even if it's an uninstalled one. One is possibly re-installing Nero and trying to uninstall it again in the hopes that the latest uninstall will not have issues, or you can try using this utility the Nero General Clean Tool http://www.nero.com/enu/tools-utilities.html by nero. One final thing to try is finding the registry key that was affected by this uninstall however I would not even suggest that if you are not an advanced level computer tech.