Same issue... here's the log.
09:16:42| Error| Error connecting to URL: n3llc.crm.dynamics.com/.../Discovery.svc Exception: Microsoft.Crm.CrmException: Logon failed because credentials are invalid ---> Microsoft.Crm.Passport.IdCrl.IdCrlException: LogonIdentityExWithUI()
at Microsoft.Crm.Passport.IdCrl.FederationLogOnManager.LogonPassport(String policy, String partner, LOGON_FLAG logonFlag)
at Microsoft.Crm.Passport.IdCrl.FederationLogOnManager.Logon(String userName, String password, String partner, String policy, String& memberName)
at Microsoft.Crm.Outlook.ClientAuth.PassportAuthProvider`1.SignIn()
--- End of inner exception stack trace ---
at Microsoft.Crm.Outlook.ClientAuth.ClientAuthProvidersFactory`1.RetrieveUserCredentialsAndSignIn(Uri endPoint, Credential credentials, Form parentWindow, Boolean retryOnError, IClientOrganizationContext context)
at Microsoft.Crm.Outlook.ClientAuth.ClientAuthProvidersFactory`1.SignIn(Uri endPoint, Credential credentials, AuthUIMode uiMode, IClientOrganizationContext context, Form parentWindow, Boolean retryOnError)
at Microsoft.Crm.Application.Outlook.Config.DeploymentsInfo.DeploymentInfo.LoadOrganizations(AuthUIMode uiMode, Form parentWindow, Credential credentials)
at Microsoft.Crm.Application.Outlook.Config.DeploymentsInfo.InternalLoadOrganizations(OrganizationDetailCollection orgs, AuthUIMode uiMode, Form parentWindow)