Tom_M wrote:
You could wire up something to your plug like an incandescent bulb. Connect a wire to the green screw and to the silver screw (ground and neutral). If the voltage drops to zero you will be okay.
Or said another way, the OP is read "ghost voltage", voltage that is really not there. This because a digital meter has extremely high input impedance, probably in the million ohm (mega-ohm) range. Old fashioned analog meters (like a Simpson 260) have an input impedance in the 10s or 100s of kila-ohm range. Enough to present a "load" and make the ghost voltage disappear.
The same problem sometime happens when trouble shooting 12VDC circuit, which is why an old fashioned incandescent test light is often be than a DMM.