WPA TKIP and 802.1x/EAP-TLS

[roby]

Hi, 

  i'm building a small wireless network. I'm using a Server Radius, for 
802.1x authentication with EAP-TLS. I used a commercial Access point and it 
works fine with WPA-TKIP and 802.1x. Problems born when i try to use a linux 
box with a Intersil Prism II PCI, with hostap driver and hostpad. It works 
fine with WEP, but when i try to use WPA-TKIP the station are authenticated 
whit 802.1x but just after that 802.11 dissaciate the stations. I'm using 
standard WinXP supplicant.
Anybody can help me? How can I set hostapd? Does hostapd work fine only with 
his hoatp-supplicant? 

Thanks for your help
Roby