MessageBox displaying twice rather once

Question

I've got an UltraComboBox control on my form, which uses the following code.

Private Sub cmbType_ValueChanged(sender as Object, e as EventArgs) Handles cmbType.ValueChanged
  If cmbType.Value <> "" Then
       If cmbType.Value = "Custom Template" Then
           Dim da As New OleDbDataAdapter("SELECT * FROM [System Settings]", con)
           Dim ds As New DataSet
           Da.Fill(ds)

           If ds.Tables(0).Rows(0).Item("enableTemplate") = False Then
               MessageBox.Show("Custom Templates have not been enabled at system level.", "Cannot Add Custom Template", MessageBoxButtons.OK, MessageBoxIcon.Information)
               cmbType.Value = ""
           End If
       ElseIf cmbType.Value = "Default Template"
           ' ...
       End If
  End If
End Sub

The issue I'm getting is that after closing the MessageBox, it sets the value to "", then iterates the code, then, for some reason, does it again but the value is back to "Custom Template", so the MessageBox shows for a second time.

Is there something wrong with the code, or is there an easier way of doing this?

EDIT

The following has not affected it, so I'm assuming that I've not interpreted @Steve's suggestion correctly.

If ds.Tables(0).Rows(0).Item("enableTemplate") = False Then
    MessageBox.Show("Custom Templates have not been enabled at system level.", "Cannot Add Custom Templates", MessageBoxButtons.OK, MessageBoxIcon.Information)
    RemoveHandler cmbType.ValueChanged, AddressOf cmbType_ValueChanged
    cmbType.Value = ""
    AddHandler cmbType.ValueChanged, AddressOf cmbType_ValueChanged
End If

EDIT 2

As per @HansPasssant's suggestion:

If ds.Tables(0).Rows(0).Item("enableTemplate") = False Then
    Me.BeginInvoke(Sub() MessageBox.Show("Custom Templates have not been enabled at system level.", "Cannot Add Custom Templates", MessageBoxButtons.OK, MessageBoxIcon.Information))
    RemoveHandler cmbType.ValueChanged, AddressOf cmbType_ValueChanged
    cmbType.Value = ""
    AddHandler cmbType.ValueChanged, AddressOf cmbType_ValueChanged
End If

This still shows the MessageBox twice.

Answer 1

If it is a bug in UltraCombo, as appears to be the case, you have 2 options:

1) Use a regular ComboBox to do the same thing - Although, it will look different so the end user may not be totally happy with this.

2) Alternatively, if you don't have lots of items in the DropDownList, you could use RadioButtons in a GroupBox to do the same thing.

Then, if the Custom Template RadioButton.Checked = True, run the same checks and output the MessageBox.

Without upgrading the controls, there really isn't a lot you can do about this, so I guess these are your only two options.