Silverlight apps not working/downloading on IIS 6.0? Try your mime types...

On IIS 6.0, there are no mime types for Silverlight by default (IIS6 was released a good deal prior to Silverlight and as with any type of content, you need to configure your web server to support it)... so you might experience that your app appears to be stuck waiting to download, but in reality it was not able to serve the request due to mime types.

Here are instructions in http://learn.iis.net/page.aspx/262/silverlight/, and a handy script, for configuring IIS 6.0 mime types to enable Silverlight.

IIS7 on Windows Server 2008 includes the appropriate mime types by default.