How to make "Period Total" in "My Work / Tasks" not editable?

Hello,
I'm working in PWA 2010 with the "Tracking mode" equal to " Hours of Work Done per Time Period". I would like to have the "Period Total" not editable  in "My Work / Tasks" .
Users should only enter their actuals in the day of the period and not as a total for the period.
Is it possible thru the customization of a view?
I don't see such options in the Manage view list.