Single sign-on for 802.1X authentication disables all non-SSO credential providers in Windows Vista and in Windows Server 2008
On a computer that is running Windows Vista or Windows Server 2008, assume that you enable the single sign-on (SSO) service for 802.1X authentication. In this scenario, all the other non-SSO credential providers are disabled. Therefore, you may be unable to authenticate by using some credential providers that are provided by Independent Software Vendors (ISVs), such as fingerprint authentication.
For more information on this issue, including potential causes, workarounds, and resolutions, see: Microsoft KB Article KB967257.