Problem with postgresql 7.2.1

Yesterday, I have upgraded postgresql database from 7.2.0 to 7.2.1
version.
Before upgrading, I have took backup from 7.2.0 and shudown the
database and
did initdb on posgresql 7.2.1. Then started the newer version (7.2.1)
and restored the data from the backup. But when we run some queries,
it is giving
the following errors.

server closed the connection unexpectedly
        This probably means the server terminated abnormally
        before or while processing the request.
The connection to the server was lost. Attempting reset: NOTICE:
Message from PostgreSQL backend:
        The Postmaster has informed me that some other backend
        died abnormally and possibly corrupted shared memory.
        I have rolled back the current transaction and am
        going to terminate your database system connection and exit.
        Please reconnect to the database system and repeat your query.

Thanks in advance and any help is appreciated.
chava