start Steam as Admin in Win 8.1
Prepare virtual P through steam
open Addonbuilder as admin
make a cube
texture with
p:\a3\signs_f\SignSpecial\Data\signspec_back_co.paa
pack as sturcture or whichever
start game with P:drive still live and no errors
Switch off P drive and restart game
error received
Warning Message: Cannot load texture
p:\a3\signs_f\signspecial\data\signspec_back_co.paa