Unbound DataGridView : Need to appear unbound ComboBox When User click a cell in second column

See more:

VB

VB10

combobox

DataGridView

Dear All,
I have a unbound DataGridView with two columns. First column is just string values.
Second column I want to display a combobox, only when user click the cell(not the whole column as DataGridViewColumn). I use the below code which is incorrect and gives me the error : Operation is not valid because it results in a reentrant call to the SetCurrentCellAddressCore function.
The first column is popuated, and the second column is empty.

The code is as below :

 Private Sub DGVFieldsMap_CellEnter(ByVal sender As Object, ByVal e As System.Windows.Forms.DataGridViewCellEventArgs) Handles DGVFieldsMap.CellEnter
        If e.ColumnIndex = 1 Then
            If cboClmCell Is Nothing Then
                Dim dgv As DataGridView = CType(sender, DataGridView)
                cboClmCell = New DataGridViewComboBoxCell
                cboClmCell.Items.Add("A")
                cboClmCell.Items.Add("B")
                cboClmCell.Items.Add("C")
                cboClmCell.Items.Add("D")
                cboClmCell.Items.Add("E")
                cboClmCell.Items.Add("F")
                dgv.Focus()
                dgv(e.ColumnIndex, e.RowIndex) = cboClmCell '[Error Here]
                isCombo = True
            End If
        End If
    End Sub

Private Sub DGVFieldsMap_CellValidating(ByVal sender As Object, ByVal e As System.Windows.Forms.DataGridViewCellValidatingEventArgs) Handles DGVFieldsMap.CellValidating
        If e.ColumnIndex = 1 Then
            Dim dgv As DataGridView = CType(sender, DataGridView)
            If isCombo Then
                isCombo = False
                cboClmCell = Nothing
                dgv(e.ColumnIndex, e.RowIndex) = New DataGridViewTextBoxCell()
            End If
        End If
End Sub

Can anybody give me a complete working example with two columns, the second column being a ComboBoxCell, but only when user clicks. Also I need to get the selected values in the DataGridView cell. Thanks In Advance.