pre-authentication problem

[IO te]

I have changed my hostapd configuration, now eth1 and ath0 are bridged together:

interface=ath0
driver=madwifi
bridge=br0
ctrl_interface=/var/run/hostapd
ctrl_interface_group=0
eapol_key_index_workaround=0
ssid=prova
auth_algs=1
wpa=2
wpa_key_mgmt=WPA-EAP
wpa_pairwise=CCMP TKIP
ieee8021x=1
own_ip_addr=<ip_accesspoint>
nas_identifier=pippo
auth_server_addr=<ip_radius>
auth_server_port=1812
auth_server_shared_secret=jacvvv
acct_server_addr=<ip_radius>
acct_server_port=1813
acct_server_shared_secret=jacvvv
rsn_preauth=1
rsn_preauth_interfaces=eth0 br0
The wpa_supplicant configuration isn't changed. When wpa_supplicant
starts I have a lot of messages like:
"Custom wireless event: 'MLME-REPLAYFAILURE.indication(keyid=1
broadcast addr=ff:ff:ff:ff:ff:ff)'
".
So it's very difficult for me to understand what's happening, but
after some time I get the following log in the ap where my station
must pre-authenticate:
IEEE 802.1X: 00:15:6d:53:a1:99 BE_AUTH entering state SUCCESS
IEEE 802.1X: Sending EAP Packet to 00:15:6d:53:a1:99 (identifier 9)
IEEE 802.1X: 00:15:6d:53:a1:99 REAUTH_TIMER entering state INITIALIZE
IEEE 802.1X: 00:15:6d:53:a1:99 AUTH_PAE entering state AUTHENTICATED
ath0: STA 00:15:6d:53:a1:99 IEEE 802.1X: authenticated - EAP type: 13
(TLS) (pre-authentication)
ath0: STA 00:15:6d:53:a1:99 WPA: pre-authentication succeeded
RSN: added PMKSA cache entry for 00:15:6d:53:a1:99
RSN: added PMKID - hexdump(len=16): 1a 9b 20 37 fe e2 fa 6f a4 0b 5a
b4 f6 ab d0 40
ath0: STA 00:15:6d:53:a1:99 WPA: added PMKSA cache entry (pre-auth)
IEEE 802.1X: 00:15:6d:53:a1:99 BE_AUTH entering state IDLE
RSN: Removing pre-authentication STA entry for 00:15:6d:53:a1:99
ath0: WPA rekeying GTK
...

What's happening? Is there anything wrong in my configurations? I'm
using hostapd version 0.5.7 and wpa_supplicant 0.4.9.

Thank you so much for your help,

Massimiliano