Emergency case: Postgres problems

Dear Sir,

I will highly appreciated if anyone could inform me how to solve the following problems in Postgres.
Specifically, sometimes there are the following messages informed by postgres.

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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.
pqReadData() -- backend closed the channel unexpectedly.
This probably means the backend terminated abnormally
before or while processing the request.
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Thank you so much for your concern

Jaruwan

PS. The Postgres version is 7.0.0 run on Red Hat Linux 7.1