Graham gave you the solution already.
Note that there is a gotcha with the .ShowHiddenText - if the user has ShowAll then it doesn't matter about the showhiddentext. To deal with that and make the code a bit shorter...
Code:
Private Sub CheckBox1_Click()
ActiveWindow.View.ShowHiddenText = False
ActiveWindow.View.ShowAll = False
ActiveDocument.Bookmarks("BMName").Range.Font.Hidden = CheckBox1.Value And CheckBox2.Value
End Sub
Private Sub CheckBox2_Click()
CheckBox1_Click
End Sub