I have disabled certificate checking on the Windows machine. Here's the log from the XP client: Reason: An internal error has occurred. Reason code: 327685 Error code: -2147023537 On the switch I see this repeated several times. The ca58 MAC is the Windows MAC, so this means that it somehow manages to answer to the RADIUS? *Mar 10 18:32:57.644: dot1x-ev(Gi0/2): Received pkt saddr =0019.6654.ca58 , daddr = 0180.c200.0003, pae-ether-type = 888e.0100.0029 *Mar 10 18:32:57.644: dot1x-ev(Gi0/2): dot1x_sendRespToServer: Response sent to the server from 0xA00006DE (0019.6654.ca58) *Mar 10 18:32:57.653: dot1x-ev(Gi0/2): Sending EAPOL packet to group PAE address *Mar 10 18:32:57.653: dot1x-ev(Gi0/2): Role determination not required *Mar 10 18:32:57.653: dot1x-ev(Gi0/2): Sending out EAPOL packet *Mar 10 18:32:57.653: dot1x-ev(Gi0/2): Role determination not required *Mar 10 18:32:57.653: dot1x-ev:Enqueued the eapol packet to the global authenticator queue *Mar 10 18:32:57.653: EAPOL pak dump rx *Mar 10 18:32:57.653: EAPOL Version: 0x1 type: 0x0 length: 0x005F *Mar 10 18:32:57.653: dot1x-ev: dot1x_auth_queue_event: Int Gi0/2 CODE= 2,TYPE= 25,LEN= 95 ----------------------------------------------------------------- Чартъри до Египет – Кайро, Хургада и круиз по Нил. 8 дни, от 275€ http://www.astralholidays.bg/pochivki/program/38/country/8.html