caching mechanisms and clean disconnect

["Josh Shamir" <josh.shamir@gmail.com>]

Hi,
I've a problem regarding the clean disconnect of a client and some caching mechanisms.
I briefly illustrate my problem :
My system is composed by freeradius and chillispot with WPA enterprise (LDAP as backend).
When i connect a client 1 to my system all works fine, except for the time taked by authentication process,
i'm using WinXP SP2 build-in supplicant. (How I can speed up this procedure?Could you suggest me some opensource supplicant?)
The problem is that when I disconnect client 1 from my system (just connecting my client to another network) and then i reconnect client1 to the system the WPA authentication failed for about 10 minutes.After this time authentication of client 1 works fine.
So I think that this fact is caused by some cache mechanism used by freeradius.
How can I make sure that a Client is disconnected in clean way and remove his session after it has disconnected inside Freeradius?

Thanks for attention
Regards, Josh