Fixing sys.InvalidOperationException: InitializeError #2104 in Silverlight 2 Beta 2

I've been working constantly on Silverlight (at a somewhat crazy pace :)) during the past few months. The site www.silverlight.net helped me a lot. I learned almost everything I know about Silverlight on this site.

I ran into this error quite frequently :
sys.InvalidOperationException: InitializeError #2104
The silverlight control won't load, and page shows blanc, even though the plugin is well installed. In fact, this error is due to the fact that the file with the extension  ".xap"  does not get saved as mime type in IIS.

To save this file correctly, Follow these steps before:
The screens are in french, but the placement of buttons and options is identical

 

  

In the two textboxes, enter the following :
  - Extension : .xap
  - Mime Type : application/x-silverlight-2-b2
That should do it ! :)

Here is the french version of this post.