Error inserting a lot of records

Hello,

We have a FreeBSD-4.3 box with Postgresql-7.0.

We also have a program that reads a txt file and
insert the datas into a postgres database.

The system works fine but, many times, when I will
insert a lot of records (about 500 recordes), it gives
me an error and the system only accept to insert many
records again after a vacuum.

When it happen,the python script shows me the follow error:

Traceback (innermost last): File "/usr/local/www/cgi-bin/admin/listalocimp.py", line 172, in ? foundfilme = fclib.query
("selectcod, titulo from filme where lower(titpesq) like lower('%%%s%%')" % (linhaseek)) File "fclib.py", line 34, in
query_pg.error: pqReadData() -- backend closed the channel unexpectedly. This probably means the backend terminated
abnormallybefore or while processing the request. 

Looking for some thing weird in pgsql.log, I've found this:

Sorry, too many clients already
Sorry, too many clients already
Sorry, too many clients already
Sorry, too many clients already
Sorry, too many clients already
Sorry, too many clients already

Could anyone help me?

Ronan