Recently we have been seeing some customers having Java issues when attempting to access the Tivoli Enterprise Portal. If the Java certificates are expired it may prevent them from being able to logon to the Tivoli Portal.
This issue may become more critical when running Java 7. The increased security in Java 7 may make it more difficult to bypass the issue.
Here is an IBM Technote on how to get the certificates updated:
Also, be aware users may not see any symptoms of their expired certificates, if they have not cleared their java cache recently. Here is a link to an IBM Technote on bypassing certificate expiration (if using Java prior to Java 7):