The TVDB API is different to the website.
The API search for TV Shows containing 'Seuss' is this:http://www.thetvdb.com/api/GetSeries.php?seriesname=seuss&language=all
By pasting the link into your browser you will notice that the page cannot be displayed,
The xml source is below, i've highlighted in red the xml error that needs to be fixed.
<?xml version="1.0" encoding="UTF-8" ?>
<SeriesName>The Wubbulous World of Dr. Seuss</SeriesName>
<Overview>This show takes the famous Dr. Seuss characters and puts them into all sorts of adventures, exploring and teaching things to the viewing audience. The Cat in the Hat has his little pack of Cat in the Hat's who he shows things to. Horton has his son who he teaches things to. It's a very educational and fun show. The Wubbulous World of Dr. Seuss originally aired on Nickelodeon and was nominated for five Daytime Emmy Awards, including Outstanding Children's Program, for three years in a row. The series combines 3-D computer animation and the puppetry of Jim Henson. The Cat in the Hat is the host of the show. He's joined by other familiar characters, such as Horton the Elephant, the Grinch, Yertle the Turtle, and a few new characters.<br>
<Overview>A series of cartoon adaptations of Theodor 'Dr. Seuss' Geisel's wonderful children's stories, beginning in 1966 with MGM Television's hit television special of 'How the Grinch Stole Christmas'.</Overview>
Simply put the document header states it is <?xml version="1.0" encoding="UTF-8" ?>
but any xml reader will raise an exception here since the <br> tag is not closed. The fix is to remove it.
XBMC works because it does not read the file as xml, but treats it as normal text and looks for patterns. With Media Companion gen1 I used a similar method, but this created it's own problems.
Easier to just mention the issue over at the TVDB forums, which will result in them fixing the bad xml.