After doing a quick search, i did not find anything - but I'll keep looking.
My gut is telling me to keep denying it - possible a "worm" type program that sends out request to random IP addresses (yours) to see if it can get through to something or not.
(hide) If you only look at some of the discussion boards on a regular basis you can add them to your favourite boards list by going to the Board page and clicking "Add to my favourite boards". (pauloaguia) (show all tips)