Liferay logs are located in <OSOP_Install_Dir>\logs (example: C:\Program Files\CA\Self Service\OSOP\logs )
While viewing the Liferay log at the time of the incident the following statements are logged:
ERROR [ServiceMgmtClientServiceDeskImpl:82] Query returned 0 contacts for email_address = "contacts email address"
ERROR [EEMLogin:120] Error during authentication in EEM
Logging into Unified Self Service portal with screen name of the format domain\userid may cause USS to time out. This happens when the user doesn't have an email address assigned to them which can be authenticated against EEM.