LT 2005 Object selection problem

[kellyh24]

During the last session of using my LT 2005, the following problem just started to happen. when I select objects one at a time to erase or copy etc, it toggles between selections. The first object selected becomes unselected when I select the next object. Have I accidently made a setting change?

[pendean]

PICKADD variable needs to be set to 1: look up usage in HELP.