ERROR: XX000: function 60821C60 returned NULL

I have an SQL job on SQL Server that dumps data to a table in
PostGreSQL. This job worked fine when it was going against a PG 8.1.3
server, but since my upgrade to PG 8.3, it has been working
intermittently. Mostly not working and erroring out with

ERROR: XX000: function 60821C60 returned NULL

I have other jobs doing similar feeds to other tables, and they still
work fine. So I can't quite figure out what is wrong with this one.
The only difference with this table is that the copy is done hourly
where as the other ones are done daily.

The table being inserted into looks like the below. If I drop the table
and recreate it, the routine starts working again. My SQL Server DTS
job uses the ODBC driver, but I tried a .NET script that uses the npgsql
driver and had the same issues. All fields are inserted into except the
the_point and gid fields. I'm going to reduce the frequency of
uploading and take out the OID to see if that makes a difference.

CREATE TABLE hbasessionsremaining
(
sessioncode character varying(17) NOT NULL,
remainingslots integer,
meetstarttime timestamp without time zone,
meetendtime timestamp without time zone,
number smallint NOT NULL,
date timestamp without time zone,
course character varying(5) NOT NULL,
classcode character varying(8) NOT NULL,
numberwaitlisted integer,
sessiongroup character varying(17),
"location" character varying(50),
locparcelid character(10),
descrip character varying(50),
locationcode character varying(3) NOT NULL,
the_point geometry,
address character varying(500),
gid serial NOT NULL,
CONSTRAINT pk_hbasessionsremaining PRIMARY KEY (sessioncode),
CONSTRAINT udx_hbasessionsremaining_gid UNIQUE (gid)
)
WITHOUT OIDS;
ALTER TABLE hbasessionsremaining OWNER TO robedev;
GRANT ALL ON TABLE hbasessionsremaining TO robedev;
GRANT ALL ON TABLE hbasessionsremaining TO dnddtsadmins WITH GRANT
OPTION;

Thanks,
Regina

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