timestamp field - select error

Hi,

I have a large table with a timestamp field.

select cf03dthr from cf03t where cf03dthr <= '2003-12-31'::timestamp ORDER
BY cf03dthr DESC LIMIT 3

cf03dthr
---------------------
2003-05-27 01:01:01
2003-05-26 09:50:55
2003-05-26 09:49:54
(3 rows)

(...) where cf03dthr <= '2003-05-27' (...)

cf03dthr
---------------------
2003-05-26 09:52:28
2003-05-26 09:50:55
2003-05-26 09:49:54
(3 rows)

* But if I do: (...) where cf03dthr <= '2003-05-26' (...)
* I get: "ERROR: convert_timevalue_to_scalar: unsupported type 16976"
* This occurs in any other dates...

If I do: (...) where cf03dthr <= '2003-05-26 09:00:00' (...), for example,
the rows returns OK, but <= '2003-05-26 06:00:00' or many other
combinations give me the same error.

Thank´s for any help.

alexandre