I actually noticed something like this in one of the snippets hosted here.
The liquid system replacement.
it works, but on boot it gives this message even though everything is installed correctly, and Everything works right. The mixtable.dat (I think thats what its called off the top of my head) is set up right, I even ended up deleting all of the mixtures made, and recreated them with the command on the mud, and still the same error message haunts me. But since it wasn't doing anything, but causing my bootup log to be ugly I have been ignoring it. But for some reason this post reminded me.
Fri May 27 9:20:04PM 2011 :: Loading mixtures
Fri May 27 9:20:04PM 2011 :: [*****] BUG: load_mixtures(): # not found (ÿ