In the web.config is a couple of lines with robots.txt telling the software to use code to answer the request. Make a backup of your web.config file and then remove those lines two lines. IIS will then respond as normal and you can put a robots.txt of your choosing in there. For instance, the ChatLink is pretty required on our site, but has cost us a lot of money since Google thinks we don't want them searching the site because of it.