ath hostap - clients assosiated, but no comms

Hi

My ath hostap device somtimes goes in a state where both my clients are 
accociated, but no UDP/IP comms between client -> hostap or client -> client. 
(if same clients connects to another AP, everything works fine)

With tcpdump -i ath0 -n -e -y IEEE802_11 I can see the received data, but with 
tcpdump -i ath0 -n -e there is nothing. 

athstats shows lots of "rx failed 'cuz of bad CRC"

Johann hugo