did you load in a setting?
some of the setting files may call up a bot that you don't have ...
or be looking in a place where it can't find it ...
I have had that happen with 'prewritten' settings ...
where the path on the author's machine is different than mine ...
ie, I have installed in a different partition or that had a special
robot location folder.
just ran 2.42, loaded lastexit.set ...
alga_minimus and the new animal_minimalis2.4 and it worked.
they died out after a bit ..
and when I do a restart, or even start a new sim ...
the animals last about 3 cycles and that's it! ???
but on the first run ... it looked promising.
~griz~