There is no autosandbox when I click the additional protection tab.
Confirmed no auto-sandbox on XP Pro SP3
Edit: Just updated my win7 netbook from 6.0.1000 to 6.0.1027, installation over the top of existing installation and the Auto-Sandbox function is present, so this looks like it is only an issue in the update on XP.
Given that they previously had a lack of activity by the auto-sandbox in XP until 6.0.1021, which seemed to be working OK. So it would be interesting to know if this is removed by accident or by design ?