Couldn't you just change the map preview/background settings in a new max.start file?
There isn't a setting to change. As soon as you load any kind of map into the Environment tab it changes whatever setting you had to Show in Viewport. Its is now the Default way for all Materials and Maps. Which also seems to be confusing the Material Editor in which map/material is suppose to be displayed in the viewport. If you click the button to turn it off, it takes anywhere from 2-3 clicks to actually turn it off.
Work around is to use the Environment tab in the Rendering settings.