a strange error

We are using PostgreSQL for more than 5 years by now and at least the
last 2-3 years we experience the following situation.

We refresh the live database on the development server using the
following shell script -

/usr/local/etc/rc.d/postgresql stop
rm -r /home/data/postgresql/data
/usr/local/etc/rc.d/postgresql initdb -D /home/data/postgresql/data
/usr/local/etc/rc.d/postgresql start
psql -f /home/database.sql -d template1 -U pgsql

(FreeBSD 6.x, PostgreSQL 8.3)

Everything works perfect, except the following -

When the db is refreshed, the first click inside the web application
that uses it (php 5.x, Apache 2.x), and some of the next clicks (i. e.
the 3rd, 5th, 8th, 12th) result in the following error -
PGSQL ERROR: server closed the connection unexpectedly
This probably means the server terminated abnormally
before or while processing the request.
After two dozen of clicks and several such messages, the application
operates normally until the next refresh.

Could somebody give us a tip what might be the reason?

Iv