The problem: combobox is databound to a DataView, first item in the dataview is DataRowView whose fields are DBNull.Value; Combo DropdownStyle = ComboBoxStyle.DropDownList

Loads fine, displays fine, selects fine, problem is to Unselect via code. Setting the SelectedIndex to 0 throws an exception. (Setting to -1 is a no-no as per msdn doco that says dont set SelectedIndex=-1 if databound)

So how to unselect without throwing an exception ?

For now i wrapped it into a try/catch to just ignore the error!

EDIT: As asked by Hubeza, i worked on sample code to post. Did a stripped down version of the original code in C# (original is in VB.NET) and could NOT reproduce it either. Converted to VB.NET and could NOT reproduce it either ! In other words, SelectedIndex = 0 does work in the stripped down version!

Currently further investigating what else could be wrong with the original code.

EDIT2: Case Closed. Call me a stupid fool if you like, and apologies for wasting anyone's time - The error was originating from MyComboBox_SelectedIndexChanged event, which i neglected to check !

May as well post the sample in case anyone finds useful.

private void LoadComboMethod() {
        DataTable dtFruit = new DataTable("FruitTable");

        //define columns
        DataColumn colID = new DataColumn();
        colID.DataType = typeof(Int32); //VB.NET GetType(Int32)
        colID.ColumnName = "ID";
        DataColumn colDesc = new DataColumn();
        colDesc.DataType = typeof(String);
        colDesc.ColumnName = "Description";

        //add columns to table
        dtFruit.Columns.AddRange(new DataColumn[] { colID, colDesc });


        //add rows
        DataRow row = dtFruit.NewRow();
        row[colID] = 1; row[colDesc] = "Apples";
        dtFruit.Rows.Add(row);

        row = dtFruit.NewRow();
        row[colID] = 1; row[colDesc] = "Bananas";
        dtFruit.Rows.Add(row);

        row = dtFruit.NewRow();
        row[colID] = 1; row[colDesc] = "Oranges";
        dtFruit.Rows.Add(row);

        //add extra blank row.
        DataRowView drv = dtFruit.DefaultView.AddNew();
        drv.EndEdit();


        //Bind combo box
        DataView dv = new DataView(dtFruit);
        dv.Sort = "ID ASC"; //ensure blank item on top
        cboFruit.DataSource = dv;
        cboFruit.DisplayMember = "Description";
        cboFruit.ValueMember = "ID";

   }


private void UnselectComboMethod() {
        if (cboFruit.SelectedIndex > 0)
        {
            cboFruit.SelectedIndex = 0;
        }
        else
        {
            MessageBox.Show("no fruit selected");
        }
}