I'd uncheck them the next time the workbook opens. It makes life easier.
Where are the checkboxes (on a single worksheet?)
How were they created (from the Forms toolbar or the control toolbox toolbar)
Option Explicit
Sub auto_open()
Dim wks As Worksheet
Dim OLEObj As OLEObject
Set wks = Worksheets("sheet1")
If wks.CheckBoxes.Count > 0 Then
wks.CheckBoxes.Value = xlOff
End If
For Each OLEObj In wks.OLEObjects
If TypeOf OLEObj.Object Is MSForms.CheckBox Then
OLEObj.Object.Value = False
End If
Next OLEObj
End Sub