Direi che potresti fare una cosa tipo questa:
codice:
Private Sub ControllaStato()
Dim c As Control
Dim ck As CheckBox
Dim n As Integer
For Each c In GroupBox1.Controls
If TypeOf c Is CheckBox Then
ck = c
If ck.Checked Then n += 1
End If
Next
If n = 2 Then GroupBox1.Enabled = False
End Sub
Private Sub CheckBox1_CheckedChanged(ByVal sender As Object, ByVal e As System.EventArgs) Handles CheckBox1.CheckedChanged
ControllaStato()
End Sub
Private Sub CheckBox2_CheckedChanged(ByVal sender As Object, ByVal e As System.EventArgs) Handles CheckBox2.CheckedChanged
ControllaStato()
End Sub
Private Sub CheckBox3_CheckedChanged(ByVal sender As Object, ByVal e As System.EventArgs) Handles CheckBox3.CheckedChanged
ControllaStato()
End Sub
Ciao