[newbie] Id "mo"

[Gustavo Viola]

Every now and then I get this message in my console:

INIT: "Id "mo" respawning too fast.  Disabled for 5 minutes."

What is this "mo"?  Why is it respawing, and how can I make it stop? 
I couldn't find anything about it in the list archives.

Any help appreciated,
Thanks.

/Gustavo.