After adding new games to The List this morning I checked what it looked like in Firefox 3 to find an empty area instead:

The Localhost version looked fine in Firefox, just as did the live IE7 version:
Since I am not a real programmer (yet) I fell in despair. I couldn't find any solution to my problem on the internet (or maybe I just don't know how to look, truth is I don't browse the web much, I'd rather suffer and waiste my precious time looking for answers inside my little brain than seek for help). About 3 hours and 50 addictive home videos of cute puppies later I remembered that yesterday I downloaded a Silverlight 2 update: bingo! It turns out my System.Web.Silverlight.dll had changed so I just uploaded it and voilà.