Do you have GateIn 3.2 on JBoss 5? If yes, it may help to configure something at datasource level, which will actually refresh DB connections. Maybe it will help to configure
valid-connection-checker-class-name and/or other similar parameters. See documentation how to configure it for Oracle 10g. You can also try to enable jmx-console and then restart datasource through jmx-console (after DB restart) and verify if it helps.