This has happened a lot of times that Visual Studio.NET 2005 looses the intellisense support. Take a look at the code below it has completly lost the support for the intellisense and does not recognize CrossPage1 which is of type Page.

public partial class CrossPage2 : System.Web.UI.Page
{
    protected void Page_Load(object sender, EventArgs e)
    {
        if (PreviousPage != null)
        {
            CrossPage1 prevPage = PreviousPage as CrossPage1;
            if (prevPage != null)
            {
                
            }
            
        }
    }
}

powered by IMHO 1.3