How to turn off ALL background tasks?

How do I turn off all the various background scanning, disk defragging, etc. that Norton does?  I've unchecked all tasks under Settings/Background Tasks.  In scheduling, I set it to manual.  Still, if I leave my pc for a couple mins, when I come back I see the box in the lower right hand corner telling me background tasks are running, not to mention my disk IO spikes up.  How can I disable all this stuff once and for all?