Portal app prompting for login to wrong client

We are deleting an obsolete QAS client (client 450). Until it is gone, we have locked all user accounts. As part of that effort we changed the client to which the QAS portal was pointing to a recently refreshed client (client 100).

We generated and imported a key; ensured the portal was pointing to the new client and bounced our servers. However now that we have made the change, our users get prompted to log on to the old client (450).

Images of UM setting and error message here:

http://picasaweb.google.com/rickc.pictures/ESSPortalProblem

We do NOT use SSO.

What have we missed that resulted in this? We need to fix it to proceed with testing.