Prefix operator error to type OID?

I'm not sure this is a PgAdminIII error or a Pg 7.3.5 error

I've created the following table:

CREATE TABLE public.prod_manager
(
  mgmid varchar(6) NOT NULL,
  mgmname varchar(35),
  email varchar(50) NOT NULL,
  CONSTRAINT prdmg_pk PRIMARY KEY (mgmid)
) WITHOUT OIDS;

with the following data
insert into prod_manager values ('000001', 'Tiny Tim', 's@s.com');
insert into prod_manager values ('000002', 'Med Tim', 'o@s.com');
insert into prod_manager values ('000003', 'Large Tim', 'p@s.com');


If I try to view the data directly from PgAdminII using the grid, I get an
error message:
Unable to identify a prefix operator  '-' for type 'oid'  You may need to
add parentheses or an explicit cast.

The data will then show.  However, if I try to update any data within the
grid, I get the same error as the above.  Everything works fine if I try to
SELECT, UPDATE, or DELETE.

Any ideas?

Patrick Hatcher
Macys.Com