whats prolly happenning is the messagebox is showing once u select radiobutton2, and once u change the value, so u can easily counter this with an if statement
Private Sub RadioButton2_CheckedChanged(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles RadioButton2.CheckedChanged
If radiobutton2.checked = true
RadioButton1.Checked = True
MsgBox("You cannot select item 2.", vbExclamation)
Example is good. It is up to you, however, to take advantage of that example, and learn from it.