One possible cause is the the DNS name doesn't match the server name. When we first setup Nfuse we ordered certs that said for example ( not the real one for obvious reasons) NFUSE - CT-xxxyy.domainname.com CSG - - CT-aaabb.domainname.com Fine - but once corporate put eveything behind the fire wall when you went to the corporate website and clicked on associate login you were redirected to a dns entry that did not match the server name of the Nfuse server. and you got the error. Now that we have an F5 in place - the certs we generated for the F5 are the real name you get to and the cert error goes away.