cache lookup failed for function 8044889

Hello list, there is migrate to postgreSQL 8.0. and I have begun to have
some errors, before had the 7.4.5:
For example I have the following function:

CREATE OR REPLACE FUNCTION "public"."find_observaciones_activos"
(integer, integer, text) RETURNS SETOF "public"."finddoc_t" AS
$body$
select set_curcfg('default');
select co_empresa, co_filial, nu_activo_fijo,sq_serialcolumn,
headline(tx_observaciones, q),
rank(vector, q)
from observaciones_activos, to_tsquery($3) as q
where co_empresa = $1 and co_filial = $2 and
vector @@ q order by rank(vector,q) desc
$body$
LANGUAGE 'sql' STABLE CALLED ON NULL INPUT SECURITY INVOKER;

and to execute this say

cache lookup failed for function 8044889

CONTEXT: sentencia SQL: «select lt.tokid, map.dict_name from
public.pg_ts_cfgmap as map, public.pg_ts_cfg as cfg,
public.token_type( $1 ) as lt where lt.alias = map.tok_alias and
map.ts_name = cfg.ts_name and cfg.oid= $2 order by lt.tokid desc;»
función SQL «find_observaciones_activos» en la sentencia 1

i drop all functions and I have recreated them again, but the problem
persist, but with the 7.4.5 version all work fine... only functions
alone the functions related with ltree or tsearch or spatial
implementation don't work

any idea please ?????

--
cordialmente,

Ing. Mario Soto Cordones