How do I fix an Entity Framework out of memory exception?

these below codes give whole data of my Rehber datas. But if i want to show web page via Gridview send me out of memory exception error.

GenoTip.BAL:

    public static List<Rehber> GetAllDataOfRehber()
        {
            using (GenoTipSatisEntities genSatisCtx = new GenoTipSatisEntities())
            {
                ObjectQuery<Rehber> rehber = genSatisCtx.Rehber;
                return rehber.ToList();
            }
        }

if i bind data directly dummy gridview like that no problem occures every thing is great!!!

 <asp:GridView ID="gwRehber" runat="server">

       </asp:GridView>

if above codes send data to Satis.aspx page:

using GenoTip.BAL;


namespace GenoTip.Web.ContentPages.Satis
{
    public partial class Satis : System.Web.UI.Page
    {
        protected void Page_Load(object sender, EventArgs e)
        {
            if (!IsPostBack)
            {
                gwRehber.DataSource = SatisServices.GetAllDataOfRehber();
                gwRehber.DataBind();
                //gwRehber.Columns[0].Visible = false;
            }
        }
    }
}

but i rearranged my gridview send me out of memory exception!!!! i need this arrangenment to show deta!!!

 <asp:GridView ID="gwRehber" runat="server">
       <Columns>
      <%-- <asp:TemplateField>
       <ItemTemplate>
        <asp:Button runat="server" ID="btnID" CommandName="select"  CommandArgument='<%# Eval("ID") %>'  Text="Seç" />
       </ItemTemplate>

       </asp:TemplateField>--%>
       <asp:BoundField DataField="Ad" HeaderText="Ad" />
       <asp:BoundField DataField="BireyID" HeaderText="BireyID" Visible="false" />
       <asp:BoundField DataField="Degistiren" HeaderText="DeÄŸiÅŸtiren" />
        <asp:BoundField DataField="EklemeTarihi" HeaderText="EklemeTarihi" />
       <asp:BoundField DataField="DegistirmeTarihi" HeaderText="DeÄŸiÅŸtirme Tarihi" Visible="false" />
       <asp:BoundField DataField="Ekleyen" HeaderText="Ekleyen" />
        <asp:BoundField DataField="ID" HeaderText="ID" Visible="false" />
       <asp:BoundField DataField="Imza" HeaderText="Imza" />
        <asp:BoundField DataField="KurumID" HeaderText="KurumID" Visible="false" />
       </Columns>
       </asp:GridView>

Error Detail :

[OutOfMemoryException: 'System.OutOfMemoryException' türünde özel durum oluşturuldu.] System.String.GetStringForStringBuilder(String value, Int32 startIndex, Int32 length, Int32 capacity) +29 System.Convert.ToBase64String(Byte[] inArray, Int32 offset, Int32 length, Base64FormattingOptions options) +146 System.Web.UI.ObjectStateFormatter.Serialize(Object stateGraph) +183 System.Web.UI.ObjectStateFormatter.System.Web.UI.IStateFormatter.Serialize(Object state) +4 System.Web.UI.Util.SerializeWithAssert(IStateFormatter formatter, Object stateGraph) +37 System.Web.UI.HiddenFieldPageStatePersister.Save() +79 System.Web.UI.Page.SavePageStateToPersistenceMedium(Object state) +105 System.Web.UI.Page.SaveAllState() +236 System.Web.UI.Page.ProcessRequestMain(Boolean includeStagesBeforeAsyncPoint, Boolean includeStagesAfterAsyncPoint) +1099