Why do you need a loop? You know exactly what you want to do:
vb.net Code:
  1. If Me.CheckBox5.Checked Then
  2.     Me.CheckBox1.Checked = False
  3.     Me.CheckBox2.Checked = False
  4.     Me.CheckBox3.Checked = False
  5.     Me.CheckBox4.Checked = False
  6. End If