Your using an Atheros chipped card? http://forums.remote-exploit.org/images/icons/icon5.gif If so make sure yours is ath0 and not ath1, ath2 etc...If it is one of the ath1, ath2..etc's..use them instead of my ath0.
***EDIT***
BTW please post your wpa supplicant for me to take a look at. And are you sure your using WPA AES and not WPA TKIP or WPA2 TKIP or WPA2 AES+TKIP???

