I use this to Save and close the workbook when the user is idle for 10 minutes:

Private Sub Worksheet_SelectionChange(ByVal Target As Range)
Dim TimeOut As Date
TimeOut = Now() + TimeValue("00:10:00")
Application.OnTime TimeOut, "KillApp"
End Sub


Sub KillApp()
ThisWorkbook.Save
ThisWorkbook.Close
End Sub

But as soon as the workbook finishes saving and closing, it opens right back
up again??? Can anyone help?