Migration - not null default '0' -> not null default 0 - confused

Hi,

I'm confused.  I'm in the process of migrating to 8.3.8.  I used pg_dump and pg_restore command for migration.
Here is my problem.
Here is my old table prior migration:
 \d activity_log
                    Table "activity_log"
 Attribute |         Type         |         Modifier
-----------+----------------------+--------------------------
 day       | integer              | not null default '0'
 hour      | integer              | not null default '0'
 group_id  | integer              | not null default '0'
 browser   | character varying(8) | not null default 'OTHER'
 ver       | double precision     | not null default '0.00'
 platform  | character varying(8) | not null default 'OTHER'
 time      | integer              | not null default '0'
 page      | text                 |
 type      | integer              | not null default '0'
 user_id   | integer              | not null default '0'


Here is my table after migration:
\d activity_log;
                          Table "public.activity_log"
  Column  |         Type         |                  Modifiers
----------+----------------------+---------------------------------------------
 day      | integer              | not null default 0
 hour     | integer              | not null default 0
 group_id | integer              | not null default 0
 browser  | character varying(8) | not null default 'OTHER'::character varying
 ver      | double precision     | not null default 0::double precision
 platform | character varying(8) | not null default 'OTHER'::character varying
 time     | integer              | not null default 0
 page     | text                 |
 type     | integer              | not null default 0
 user_id  | integer              | not null default 0

Now, the source code doesn't work any more. Here is the SQL - INSERT INTO activity_log
(day,hour,group_id,browser,ver,platform,time,page,type,user_id)VALUES
(20100330,'16','','MOZILLA','5.0','Win','1269990036','/index.php','0','');
and pgsql returned "ERROR:  invalid input syntax for integer: """.  My understanding is that if the value is null, then
itshould set both the group_id=0 and user_id=0.  But it didn't do it.   With the old table, this SQL statement would
work.

Any suggestions on what I need to do for the not null default values?

I'm running on Postgres 8.3.8 and RHEL 3.9.

Thanks
Mary Wang