>Are you sure you have not defined your own class named 'Shell' that is somehow referenced in that project? Simple repro:

Partial Public Class _Default
>    Inherits System.Web.UI.Page
>    Protected Sub Page_Load(ByVal sender As Object, ByVal e As System.EventArgs) Handles Me.Load
>        Shell("Test")
>    End Sub
>End Class
>
>Public Class Shell
>End Class

No, but it could be related to the project properties. The project that it works is a desktop project. The other one, the one which is not working, is a DLL project. I assume the EXE project is probably containing a reference to a module which would be needed for the Shell to work in the DLL project. Or, maybe, by default, this cannot be used in a DLL project.