problem with creating/dropping tables and plpgsql ?

I'm pretty new to postgresql.. I'm using a fresh compile/install of postgresql 7.1.2 without any special options.. but here's my problem:

semantic=# create temp table ttmptable(lookup_id int, rating int);
CREATE
semantic=# SELECT doEverythingTemp(20706,2507);
doeverythingtemp
------------------
1
(1 row)
semantic=# DROP table ttmptable;
DROP
semantic=# create temp table ttmptable(lookup_id int, rating int);
CREATE
semantic=# SELECT doEverythingTemp(20706,2507);
ERROR: Relation 4348389 does not exist

--- schema --

CREATE FUNCTION doEverythingTemp(int,int) RETURNS int AS '
DECLARE
rrec RECORD;
userid int;
lookupid int;
rrating int;
ruser int;
BEGIN
userid := $1;
lookupid := $2;
FOR rrec IN SELECT webuser_id,rating FROM rating WHERE webuser_id!=userid AND lookup_id=lookupid;
rrating:=rrec.rating;
ruser:=rrec.webuser_id;
INSERT INTO ttmptable SELECT lookup_id,rrating*rating FROM rating WHERE webuser_id=ruser AND lookup_id!=lookupid;
END LOOP;
RETURN 1;
END;' LANGUAGE 'plpgsql'

Table "rating"
Attribute | Type | Modifier
-------------+---------+----------------------------------------------------------
webuser_id | integer | not null default '0'
category_id | integer | not null default '0'
lookup_id | integer | not null default '0'
rating | integer | not null default '0'
rating_id | integer | not null default nextval('"rating_rating_id_seq"'::text)
Indices: rating_category_id_idx,
rating_lookup_id_idx,
rating_rating_id_key,
rating_webuser_id_idx

I've tried regular tables, creating the table from within the function, and a few other things.. no luck. Does anyone have ANY idea how I can either redesign this query or make the create/drop thing work properly?

Thanks,
(::) Bob Ippolito