Mass update permission error

We have a scheduled mass update for license (a custom record). The update works fine in the UI (I am logged in as administrator), however, when it tries to run per the schedule we get the error:

"Mass Update Failure : Populate Lic Order Start Date... Permission Violation: You need a higher permission for custom record type License to access this page. Please contact your account administrator."

My guess is that when running on a scheduled basis the mass update runs as 'system' (sort of like a scheduled script). How can I make the mass update run as a specific role or user OR how can I make the custom record editable by 'system'?