Postgresql 7.0 JDBC exceptions - broken connections ?

Hello, 

As I told you in an former mail I'm trying to migrate an application to use
PostgreSQL 7.0. The application now seems to be working pretty well and I
have 5 users that have been testing our web application with the PostgreSQL
database for the past 24 hours. 

The application runs with a connection pool, but after some time some of
these connections seems to be broken. Ie. only some of the queries work - I
will change the connection pool code to handle this, but I would like to
know if anybody know why the connections gets into an unusable state. Could
it be back crashes or similar things ? I'm turning on debugging for the
database server to see if can find anything there, but anyway here is the
exception I get :

select distinct entity.*,location.loc_id,location.loc_name
from entity,locationmap,location,entityindex2 as e0
where locationmap.ent_id=entity.ent_id and locationmap.loc_id=location.loc_id and e0.ei_word='kjøttbørsen' and
e0.ent_id=entity.ent_idand ENT_STATUS=4
 
order by ent_title,location.loc_name,location.loc_id
Unknown Response Type uat java.lang.Throwable.fillInStackTrace(Native Method)at
java.lang.Throwable.fillInStackTrace(CompiledCode)at java.lang.Throwable.<init>(Compiled Code)at
java.lang.Exception.<init>(CompiledCode)at java.sql.SQLException.<init>(SQLException.java:98)at
org.postgresql.util.PSQLException.<init>(PSQLException.java:42)atorg.postgresql.Connection.ExecSQL(Compiled Code)at
org.postgresql.jdbc2.Statement.execute(CompiledCode)at org.postgresql.jdbc2.Statement.executeQuery(Compiled Code)at
EntityActions.searchIndexImpl(CompiledCode)at SearchFasterServerEvents.serverRequest(Compiled Code)at
progress.apptivity.server.abServer.serverRequest(CompiledCode)at
progress.apptivity.server.abQuerySetImpl.serverRequest(CompiledCode)at
progress.apptivity.client.iiop._abQuerySetImplBase.invoke(CompiledCode)at
IE.Iona.OrbixWeb.CORBA.ServerDispatcher.dispatch(CompiledCode)at
IE.Iona.OrbixWeb.CORBA.ServerDispatcher.system_dispatch(CompiledCode)at
IE.Iona.OrbixWeb.CORBA.BOAImpl.continueThreadDispatch(CompiledCode)at
IE.Iona.OrbixWeb.CORBA.ORB.continueThreadDispatch(CompiledCode)    at
progress.apptivity.server.iiop.ow.a25.run(CompiledCode)at java.lang.Thread.run(Compiled Code)
 


Regards, 
Gunnar