ERROR: fmgr_info: function 0: cache lookup failed

Hi,
I want retrieve ROW of tables by their OID,
to do thise I made as folowing :
CREATE TABLE tab1 (X int4, Y varchar);
CREATE

CREATE FUNCTION tabrecord (OID) returns RECORD AS 'BEGIN RETURN(SELECT *
FROM tab1 WHERE OID = $1) END;' language 'plpgsql';
NOTICE: ProcedureCreate: type 'record' is not yet defined
NOTICE: ProcedureCreate: type 'record' is not yet defined
CREATE

select tabrecord (2542 :: oid);
ERROR: fmgr_info: function 0: cache lookup failed
ERROR: fmgr_info: function 0: cache lookup failed

could you help me to solve this problem please,
Mourad.