can't connect postgresql server. max connection exceeded.

Hello. I have a question about max connection.

i use postgreSQL 7.0.3 and up to now i use well.

but, this time i encountered the max connection problem.

my default max connection value is 32.

that is, if 32 connections are established, no other connection can't be
established..

then once 32 connections are established, processes that contain postgresql
connection are not operational. 32 processes have connections are not ended.
so system can't create any new connection to postgreSQL.

why this situation do occur?

have any suggestion that figure out this problem???