>Hi,
>
>I am trying to get into using SilverLight and am looking into using the CSLA.NET for SilverLight stuff. When I open and try to build one of the sample applications that comes with it I get these errors:
>
>Error 1 The type 'System.Collections.ObjectModel.ObservableCollection`1' is defined in an assembly that is not referenced. You must add a reference to assembly 'System.Windows, Version=2.0.5.0, Culture=neutral, PublicKeyToken=7cec85d7bea7798e'. C:\Documents and Settings\frank\My Documents\Visual Studio 2008\Projects\csla\CslaLight\cs\InventoryDemo\InvDal\WarehouseList.cs 11 33 InvDal
>
>Error 2 The type 'System.ComponentModel.IEditableObject' is defined in an assembly that is not referenced. You must add a reference to assembly 'System, Version=2.0.5.0, Culture=neutral, PublicKeyToken=7cec85d7bea7798e'. C:\Documents and Settings\frank\My Documents\Visual Studio 2008\Projects\csla\CslaLight\cs\InventoryDemo\InvDal\ProductEdit.cs 13 31 InvDal
>
>Error 3 The type 'System.ComponentModel.INotifyPropertyChanged' is defined in an assembly that is not referenced. You must add a reference to assembly 'System, Version=2.0.5.0, Culture=neutral, PublicKeyToken=7cec85d7bea7798e'. C:\Documents and Settings\frank\My Documents\Visual Studio 2008\Projects\csla\CslaLight\cs\InventoryDemo\InvDal\ProductDetail.cs 13 33 InvDal
>
>I have tried to find System.Windows.dll and System.dll without luck.
>
>I have double checked that everything is installed. Can anybody provide me with some ideas as to what could be causing this problem, please?
>
>Thanks

Install .Net Framework 3.5 SP1 and then try adding a reference in the project to WindowsBase and see if that fixes it. Also, did you do the project by scratch or did you open an existing sample app and if so, were you prompted to convert it?