unwanted shutdown after scan - seems bugish

Have avast! 5.0.418 on Vista Home Prem, 32-bit. I really like this v5 and thanks to the collaborators who made it.

This went wrong the other day… after a manually started full scan - BTW not my first one using v5 - avast! paused. It needed my response to a popup telling me my scan settings indicate it will shut down my system unless I click the ‘cancel’ button in the popup.

OK, so I canceled the shutdown then went looking for the setting mentioned.

The relevant checkbox had been unchecked all the while - capture image attached.

So it’s a minor annoyance. I only found that one checkbox to be relevant. Have I missed something, or is something misfiring here?