Date time problem with timstamp with no timezone data type

Hi,

We have weiered problem with one timestamp(without timezone) data type
column(updated_date) in one table.  We insert a row into this table with
current time once and susequently update it many times with current time.
What happens is with each update the updated_date is increased by 7 hours.
We are in PDT timezone and for initial insert +7 hours is fine but
subsequent updates increasing it by +7 hours is wiered. What should we do
here?

We are using stable pgjdbc2.jar and we are using postgres7.2.1.

Thanks
Yuva