Hello, We have SSO software called CAS configured for SPNEGO authentication. Clients with windows XP are working correctly with IE and Firefox, authenticating users by NTLM. Clients in Windows 7 are trying to authenticate using Kerberos, and we get this error in CAS: jcifs.spnego.AuthenticationException: Error performing Kerberos authentication: java.lang.reflect.InvocationTargetException... GSSException: Defective token detected (Mechanism level: GSSHeader did not find the right tag)... Looking for information, I have found: "Negoex is needed by Microsoft technology for things such as active directory and can not be disabled. And the latest Java core beta-s does not yet accept it. Everything works fine with Windows XP. This problem only appears with Windows 7 or newer."(http://sourceforge.net/projects/spnego/forums/forum/1003769/topic/3763057) So, I am wondering if there is some news about that: Could NegoEx in Windows 7 be disabled to avoid Java errors? Any tweak in Java to avoid NegoEx error? Java version able to work with NegoEx? In an other way, can Windows 7 be force to use NTLM authentication for SPNEGO in Internet Explorer intead of Kerberos? Any help will be apreciated.