That might mean you are brushing the touchpad with the bottom or palm of your hand. Disabling it when using the KB is the right way to prevent it. You might have a setting that will automatically disable it when typing. Check your mouse and kb settings. See your manual online at Dell Support for directions.

Open the Control Panel, then the "Mouse" icon, then the "Pointer Options", then UNCHECK the box next to "Enhance Pointer Precision". Apply, then OK.

Hope this helps.