I would start by running the utility to restart all the services it maybe one of the service has stalled, or possible restarting the UC server. Also might be helpful if you could provide additional details such as is the admin UC Client on the server itself or is it on a different system and a user version of the client. Has anything changed on the account trying to run it, i.e. password change, new account. Has there been any changes to the firewall on the system running the client Windows FW maybe blocking the application from connecting to the DB.