Please see this link for the entire details of the cause and solution.
Resolving the problem
Disable the IBM Websphere Application Server 8.x Security Integration feature for WorkplaceXT:
- In the IBM Websphere Administrative Console navigate to Applications->Websphere Enterprise Applications -> WorkplaceXT -> Session Management
- Check the Override session Management checkbox
- Uncheck the Security integration option
- Save the changes
- Restart the WorkplaceXT application