Question about JDBC?

Hi sometimes I catch this exceptions in my aplications:
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java.sql.SQLException: IOError while reading from backend:
java.net.SocketException: Broken pipe
at postgresql.PG_Stream.ReceiveChar(PG_Stream.java:183)
at postgresql.Connection.ExecSQL(Connection.java:668)
at postgresql.Connection.setAutoCommit(Connection.java:377)
at actas2003.partidos.Partidos.doGet(PartidosPoliticos.java:45)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:499)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:588)
at
org.apache.jserv.JServConnection.processRequest(JServConnection.java:335)

at
org.apache.jserv.JServConnection.run(JServConnection.java:197)
at java.lang.Thread.run(Thread.java)
java.sql.SQLException: Error flushing output: java.io.IOException:
Broken pipe
at postgresql.PG_Stream.flush(PG_Stream.java:370)
at postgresql.Connection.ExecSQL(Connection.java:659)
at postgresql.Connection.setAutoCommit(Connection.java:377)
at
actas2003.funcionarios.catalogo.BuscaFun.doGet(BuscaFun.java:67)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:499)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:588)
at
org.apache.jserv.JServConnection.processRequest(JServConnection.java:335)

at
org.apache.jserv.JServConnection.run(JServConnection.java:197)
at java.lang.Thread.run(Thread.java)
java.sql.SQLException: Error flushing output: java.io.IOException:
Broken pipe
at postgresql.PG_Stream.flush(PG_Stream.java:370)
at postgresql.Connection.ExecSQL(Connection.java:659)
at postgresql.Connection.setAutoCommit(Connection.java:377)
at
actas2003.funcionarios.catalogo.DatosFun.doGet(DatosFun.java:68)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:499)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:588)
at
org.apache.jserv.JServConnection.processRequest(JServConnection.java:335)

at
org.apache.jserv.JServConnection.run(JServConnection.java:197)
at java.lang.Thread.run(Thread.java)
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We don't know if the error is in the driver or is our aplications, the
extrange is that is not common error, and when ocurred is solved by
restarting postgres...

The thing that we want to know is if someone can help us to found the
reason to this error to take actions about it.

Thanks for all.

Alex...