Norton Internet Security background scan

I know how to disable it, but I just want to set it so, as not to disturb running programs. As of this moment, Norton is performing a disk optimisation my notebook. After a few minutes, Norton starts a background task "while your computer is idle". However, the computer is not idle, as it is already performing a task.

The same applies during back-ups, unless Silent Mode enabled. Is it possible to stop Norton from doing the "idle tasks", whilst others are running?