Random crashes on getConnection

I've traced the crash to:

org.postgresql.core.v3.ConnectionFactoryImpl.readStartupMessages(PGStream,
ProtocolConnectionImpl, Logger) line: 470

For some reason, client_encoding gets changed back and forth from
UNICODE to LATIN9. When it's LATIN9, it causes the exception.

In my connection URL/parameters I do not force any encoding. LATIN9 is
the encoding the database is set to. What can be causing this switch?

(Message that caused the exception: beresp = 83 (E),
client_encoding=LATIN9)

Any ideas?

-----------
>I get random exceptions on GetConnection() on a Quartz-based job.
>Sometimes everything works, and sometimes I get a "Protocol Error.
>Session setup failed". Does anybody know what might be happening?

>Client: Both postgresql-8.3-604.jdbc4.jar and
>postgresql-8.4dev-700.jdbc4.jar.
>Server: Postgres 8.1. The databases are stored in LATIN9 encoding.
>JVM: java-6-sun-1.6.0.12

>SEVERE: com(dot)androme(dot)phemium(dot)statistics(dot)EligibleCustomerList(at)3b1d04
>org.postgresql.util.PSQLException: Protocol error. Session setup >failed.
> at
>org.postgresql.core.v3.ConnectionFactoryImpl.readStartupMessages(ConnectionFactoryImpl.java:481)
> at
>org.postgresql.core.v3.ConnectionFactoryImpl.openConnectionImpl(ConnectionFactoryImpl.java:101)
> at
--
<b>Ramon Poca</b> <br/>
<a href="mailto:ramon(dot)poca(at)androme(dot)es">ramon(dot)poca(at)androme(dot)es</a>