Hmm, and the filter that kicks in, that is from Cablevision? How can you tell it kicks in (I've never seen that)? Just looking for clues.
I am also wondering if it needs to be one of your computers that is the culprit (if someone was able to get a connection, they could bulk load spam, but I'm not sure if that would trigger your 'filter').
Strange.
If it is one of your computers, then if you leave them all on, and disable the wireless you would still see an issue right (assuming they have wired connections)? Might want to test that.