In my site I prefix the images and links with the domain of the site for better SEO using the code below:

public static string GetHTTPHost()
        {
            string host = "";

            if (HttpContext.Current.Request["HTTP_HOST"] != null)
                host = HttpContext.Current.Request["HTTP_HOST"];

            if (host == "site.co.uk" || host == "site.com")
            {
                return "http://www." + host;
            }

            return "http://"+ host;
        }

This works great, but for some reason, lots of links have now changed to http://www.baidu.com/...

There is no sign of this in any of the code or project, the files on the server also have a change date when i last did the publish at 11 yesterday, so all the files on there look fine. I am using ASP.net and Umbraco 4.7.2

Does anyone have any ideas? thanks