Loads of people have had problems with this episode. You should use the search engine instead of posting a new topic. It's been repeated countless times already +_+;

But in answer, try using G-Spot for a diagnosis, and use the AviC to change to the DivX codec, or try the other way, which is to install some sort of codec pack. Sorry if i seem very hazy on the details, but you should take a look around first, you will see all this in the other topics =P