There are two security level sliders in Defence Plus ~ Defense Plus Settings, the defence plus security level slider and the sandbox security level slider.
Moving the Sandbox security level slider to disabled, disables the automatic and manual sandboxes.
Moving the Defense plus security level slider to disabled disables the manual but not the automatic sandboxes.
Choosing to ‘Turn off D+ permanently’ and rebooting, disables the automatic and manual sandboxes.
Checked: 07 October 2010 to ensure reflects CIS version 5.8 RC2