Io exception: Connection reset

Hi

I have created a webdynpro java applciation connected to Custom Oracle Database.

for this in Visual Admin ,in the JDBC Connector Service , i have created DataSource.

Details:

Driver Name: SYSTEM_DRIVER

JDBC Version 1.x

Driver Class: oracle.jdbc.driver.OracleDriver

The Connection works fine.

But after some time has elapsed it throws errors.

java.sql.SQLException: Io exception: Connection reset

java.sql.SQLException: Closed Connection

if i login to visual admin and test the connection,in first attempt it fails but in second attemp it succeeds.

and then it works fine for siome time.

and again same problem appears.

my Portal Server is EP7 sp18.

and Custom Oracle Database is 9i.

what can be the reason?

Regards

Rajendra