Some troubles with Access and bool

I have a small table in my 7.4 Postgres database:

CREATE TABLE jmbool
(
icompt int4,
mybool bool
)
WITHOUT OIDS;

I have MS Access 2003. My ODBC Driver a the option "treats bool as
char" unchecked.
IN MS Access, I can add a record but it not possible to delete any record:
error message: The Microsoft Jet database engine stopped the process
because you and another user are attempting to change the same data at
the same time.

Of course, I am alone on the Postgres database.
How to solve this blocking issue ?
Thanks for your answers.

--
Jean-Max Reymond
CKR Solutions
http://www.ckr-solutions.com