RE: Prompting for credentials

Is it possible that the information is being cached on the client system? So can anyone help me?

Windows XP caches credentials for PEAP. If you want it to reprompt, you'll need to delete a registry key (HKCU\Software\Microsoft\Eapol\UserEapInfo). See http://support.microsoft.com/kb/823731 for more info. Vista has the ability to control caching of credentials (i.e., you can tell it not to do so).