java.sql.SQLException: Io 错误: Connection refused

java.sql.SQLException: Io 异常: Connection refused
Tomcat 5起动时报下面的错误，但是应用程序可以正常，不过运行一段时间后，会连不上数据库？请教各位大侠！

SQL code

java.sql.SQLException: Io 异常: Connection refused(DESCRIPTION=(TMP=)(VSNNUM=153092352)(ERR=12500)(ERROR_STACK=(ERROR=(CODE=12500)(EMFI=4))(ERROR=(CODE=12540)(EMFI=4))(ERROR=(CODE=12560)(EMFI=4))(ERROR=(CODE=510)(EMFI=4))(ERROR=(BUF='32-bit Windows Error: 8: Exec format error'))))        at oracle.jdbc.dbaccess.DBError.throwSqlException(DBError.java:134)        at oracle.jdbc.dbaccess.DBError.throwSqlException(DBError.java:179)        at oracle.jdbc.dbaccess.DBError.throwSqlException(DBError.java:333)        at oracle.jdbc.driver.OracleConnection.<init>(OracleConnection.java:404)        at oracle.jdbc.driver.OracleDriver.getConnectionInstance(OracleDriver.java:468)        at oracle.jdbc.driver.OracleDriver.connect(OracleDriver.java:314)        at java.sql.DriverManager.getConnection(Unknown Source)        at java.sql.DriverManager.getConnection(Unknown Source)        at org.logicalcobwebs.proxool.DefaultConnectionBuilder.buildConnection(DefaultConnectionBuilder.java:39)        at org.logicalcobwebs.proxool.Prototyper.buildConnection(Prototyper.java:159)        at org.logicalcobwebs.proxool.Prototyper.sweep(Prototyper.java:102)        at org.logicalcobwebs.proxool.PrototyperThread.run(PrototyperThread.java:44)