I haven't been able to resolve this issue yet but Oracle says its a Bug in 10.1.4.01 IDM which we are using and it can be resolved after applying patch 5867734. and make sure GenericPageBean.class file has the date 5/9/2007 on it. To get that use following command :
cd %ORACLE_HOME%/j2ee/OC4J_SECURITY/applications/sso/web/WEB-INF/lib$ORACLE_HOME/jdk/bin/jar tvf ossoui.jar
Although it didn't resolved my issue, but I felt sharing this info.
Happy Troubleshooting !!!