If you crate a new custom splash screen page (Silverlight 1.0 JScript page) for the Silverlight and build the project, you may get following error.
Error 1 Project file must include the .NET Framework assembly 'WindowsBase, PresentationCore, PresentationFramework' in the reference list. SilverlightApplication.Web
To resolve the error, change the Build Action of these pages to "Content". To know how to create custom splash screen in Silverlight, read http://www.dotnetfunda.com/articles/article1087-how-to-create-a-custom-splash-loading-screen-in-silverlight-.aspx