Hi Greg.
I have a few options active under the Optimize tab. BrowserFriendly, SmartFeed, and FeedFlare.
I did just try to set up the Title burner option, figuring if there was a title problem with the link I could just get around it. When I added a new title, I again got the error:
The URL does not appear to reference a valid XML file.
Wish that error message was more descriptive.