BOBJ SSO issue with Portal on Multi User logon

Hi,

I have establised a SSO between Portal 7.4 and BOBJ as per the below steps.

http://scn.sap.com/community/enterprise-portal/blog/2013/04/05/integration-of-bobj-with-sap-portal

The SSO is working fine while tested in individual browser with seperate user ids.

However, I am seeing a Java Dump error, when it is tested for multiple user one after the other in the same browser.

1. Login as User1, Access BI LaunchPad, Log of the User1.

2. Login as User2, Access BI LaunchPad, shows java dump. Clicking Refresh loads the BI Launchpad correctly.

Below is the java dump error details

java.lang.IllegalStateException: getAttribute: Session already invalidated

Please let me know, if there is any suggestions to get this dump removed for first time.