Hi guys, I've created a new Silverlight 3 Business Application with VS 2008. The creation has completed correctly. When I try to open the xaml, it opens but in meanwhile this error is shown:

Failed to load metadata assembly System.Windows.Controls.Data.Input.Design, Version=2.0.5.0, Culture=neutral, PublicKeyToken=31bf3856ad364e35. Exception message: Unable to load one or more of the requested types. Retrieve the LoaderExceptions property for more information.. Stack Trace:
at System.Reflection.Module._GetTypesInternal(StackCrawlMark& stackMark) at System.Reflection.Assembly.GetTypes() at MS.Internal.Package.MetadataLoader.RegisterDesignTimeMetadata(Assembly assembly, LogCallback logger)An exception of type ArgumentNullException was caught when calling IRegisterMetadata on type System.Windows.Controls.Data.Input.VisualStudio.Design.MetadataRegistration. Exception Message: Value cannot be null. Parameter name: type. Stack Trace: at Microsoft.Windows.Design.Metadata.AttributeTableBuilder.AddCallback(Type type, AttributeCallback callback)
at System.Windows.Controls.Data.Input.VisualStudio.Design.MetadataRegistration.AddAttributes(AttributeTableBuilder builder) at System.Windows.Controls.Design.Common.MetadataRegistrationBase.BuildAttributeTable() at System.Windows.Controls.Data.Input.VisualStudio.Design.MetadataRegistration.Register() at MS.Internal.Package.MetadataLoader.RegisterDesignTimeMetadata(Assembly assembly, LogCallback logger)Failed to load metadata assembly System.Windows.Controls.Design, Version=2.0.5.0, Culture=neutral, PublicKeyToken=31bf3856ad364e35. Exception message: Unable to load one or more of the requested types. Retrieve the LoaderExceptions property for more information.. Stack Trace:
at System.Reflection.Module._GetTypesInternal(StackCrawlMark& stackMark) at System.Reflection.Assembly.GetTypes() at MS.Internal.Package.MetadataLoader.RegisterDesignTimeMetadata(Assembly assembly, LogCallback logger)Failed to load metadata assembly System.Windows.Controls.Navigation.Design, Version=2.0.5.0, Culture=neutral, PublicKeyToken=31bf3856ad364e35. Exception message: Unable to load one or more of the requested types. Retrieve the LoaderExceptions property for more information.. Stack Trace:
at System.Reflection.Module._GetTypesInternal(StackCrawlMark& stackMark) at System.Reflection.Assembly.GetTypes() at MS.Internal.Package.MetadataLoader.RegisterDesignTimeMetadata(Assembly assembly, LogCallback logger)

Why? Any solutions? Thank you in advance.