I'd try starting the game as root for once, and see if the problem still arises. If not, then it's a permission problem (which I guess it is, but just do the above to make sure).
IF it appears to be a permission problem, then run:
Code:
chown <your username here>.users /home/users/ -Rv
chown <your username here>.users /home/users/. -Rv
chmod a+rwx <your username here>.users /home/users/.<the et folder here> -Rv
Try those, and if it still doesn't work then you didn't follow the instalation procedure properly :-).
Greets, Target
ps. If this still doesn't work, then you can try to chmod the whole /usr/local/games/wolfenstein map to your user & +rwx permissions, but this is generally not recommend. Preferably dont use this, as it shouldn't be neccesary normally.