I have a page which returns the ContentType name and the Url of every page on our site, its purpose is for an automated test to browse each URL and check that a 200 is returned. This page uses the following to return its friendly URL:

public UrlBuilder GetFriendlyUrl(PageData page)
{  
  UrlBuilder urlBuilder = new UrlBuilder(page.LinkURL);  
  Global.UrlRewriteProvider.ConvertToExternal(urlBuilder, page.PageLink, Encoding.UTF8);
  return urlBuilder;
}

In the case of one particular ContentType, this returns a url that looks like this, in every instance of that ContentType :

"/link/8b5c1e86a4b54110ba7a311a691de448.aspx?id=9485&epslanguage=en"

Other points to note...

• This works correctly for all of the pages on our site except for pages of this contenttype.
• If I call UrlResolver.Current.GetUrl on its contentLink, it returns null. 
• There is nothing different about this contenttype compared to other types we are using.
• This worked correctly before we upgraded from 6R2 to 7.5.
• This ContentType was created after we upgraded, although other types have been created since then, and they work fine. 

I've tried a load of OOTB ways of getting external URL from ContentReference, PageData etc and nothing returns a nice, friendly URL. When our automated test tries to browse to this dodgy-looking URL, it fails. 

Can anyone enlighten me as to what's going on here?

Cheers