Postgres Triggers issue

I have a strange problem we noticed the other day with triggers. We're
running 8.3.3 on Solaris 10 (intel) and have a feed that comes in
regularly to populate a table we're working on. The feed works just
fine inserting rows however the following trigger stops the feed until
we remove the trigger. Any thoughts on what I'm doing wrong here?

Thanks!

---

CREATE OR REPLACE FUNCTION r.m_t()
RETURNS trigger AS
$BODY$
BEGIN
INSERT INTO temp_m_t VALUES (NEW.*,1+1);
RETURN NULL;
END;
$BODY$
LANGUAGE 'plpgsql';

CREATE TRIGGER tafter
AFTER INSERT OR UPDATE
ON r.m_a
FOR EACH ROW
EXECUTE PROCEDURE r.m_t();