JBoss Portal 2.6.4 & PostgreSQL 8.3

JBoss Portal 2.6.4 を入れてみました。
hsql,mysqlでは問題なく動作するようですが、PostgreSQL 8.3 を使おうとすると下のようなエラーが出ます。 JDBCも新しい8.3のものに変更しているので、これで動いてくれないとがっかりです。　googleしてみましたが、この手のエラーについて幾つか見つかったものの、jdbcの問題によるものみたいで、参考にはなりませんでした。　当該のSQLをコピペで直接PostgreSQLで実行しても、すんなり動くので ? に挿入される文字列の問題なのか、本当にjdbcのimplementationの問題なのかは分かりません。　Postgresql側で詳細なlogを取ってみる方法もあるのでしょうが、、、。

2008-02-28 10:17:16,939 DEBUG [org.hibernate.SQL] insert into JBP_PORTAL_OBJECT_PROPS (OBJECT_KEY, NAME, jbp_VALUE) values (?, ?, ?)
2008-02-28 10:17:16,940 DEBUG [org.hibernate.persister.collection.AbstractCollectionPersister] done inserting collection: 16 rows inserted
2008-02-28 10:17:16,940 DEBUG [org.hibernate.jdbc.AbstractBatcher] Executing batch size: 1
2008-02-28 10:17:16,940 DEBUG [org.hibernate.jdbc.AbstractBatcher] about to close PreparedStatement (open PreparedStatements: 1, globally: 1)
2008-02-28 10:17:16,941 DEBUG [org.hibernate.jdbc.ConnectionManager] skipping aggressive-release due to flush cycle
2008-02-28 10:17:16,941 DEBUG [org.hibernate.jdbc.ConnectionManager] aggressively releasing JDBC connection
2008-02-28 10:17:16,941 DEBUG [org.hibernate.jdbc.ConnectionManager] releasing JDBC connection [ (open PreparedStatements: 0, globally: 0) (open ResultSets:
0, globally: 0)]
2008-02-28 10:17:16,941 DEBUG [org.hibernate.jdbc.AbstractBatcher] about to open PreparedStatement (open PreparedStatements: 0, globally: 0)
2008-02-28 10:17:16,941 DEBUG [org.hibernate.jdbc.ConnectionManager] opening JDBC connection
2008-02-28 10:17:16,941 DEBUG [org.hibernate.SQL] select objectnode0_.PK as PK64_, objectnode0_.PATH as PATH64_, objectnode0_.NAME as NAME64_, objectnode0_.P
ARENT_KEY as PARENT4_64_ from JBP_OBJECT_NODE objectnode0_ where objectnode0_.PATH=? or objectnode0_.PATH is null
2008-02-28 10:17:17,011 DEBUG [org.hibernate.jdbc.AbstractBatcher] about to close PreparedStatement (open PreparedStatements: 1, globally: 1)
2008-02-28 10:17:17,011 DEBUG [org.hibernate.jdbc.ConnectionManager] aggressively releasing JDBC connection
2008-02-28 10:17:17,011 DEBUG [org.hibernate.jdbc.ConnectionManager] releasing JDBC connection [ (open PreparedStatements: 0, globally: 0) (open ResultSets:
0, globally: 0)]
2008-02-28 10:17:17,014 DEBUG [org.hibernate.util.JDBCExceptionReporter] could not execute query [select objectnode0_.PK as PK64_, objectnode0_.PATH as PATH6
4_, objectnode0_.NAME as NAME64_, objectnode0_.PARENT_KEY as PARENT4_64_ from JBP_OBJECT_NODE objectnode0_ where objectnode0_.PATH=? or objectnode0_.PATH is
null]
org.postgresql.util.PSQLException: An I/O error occured while sending to the backend.
at org.postgresql.core.v3.QueryExecutorImpl.execute(QueryExecutorImpl.java:218)
at org.postgresql.jdbc2.AbstractJdbc2Statement.execute(AbstractJdbc2Statement.java:451)
at org.postgresql.jdbc2.AbstractJdbc2Statement.executeWithFlags(AbstractJdbc2Statement.java:350)
at org.postgresql.jdbc2.AbstractJdbc2Statement.executeQuery(AbstractJdbc2Statement.java:254)
at org.jboss.resource.adapter.jdbc.WrappedPreparedStatement.executeQuery(WrappedPreparedStatement.java:236)
at org.hibernate.jdbc.AbstractBatcher.getResultSet(AbstractBatcher.java:186)
at org.hibernate.loader.Loader.getResultSet(Loader.java:1787)