ath0: stuck beacon; resetting (bmiss count 4)

Mar  5 19:27:48 daedalus kernel: ath0: stuck beacon; resetting (bmiss 
count 4)
Mar  5 19:28:19 daedalus last message repeated 95 times
Mar  5 19:30:20 daedalus last message repeated 359 times
Mar  5 19:32:54 daedalus last message repeated 481 times
Mar  5 19:32:54 daedalus kernel:
Mar  5 19:32:55 daedalus kernel: ath0: stuck beacon; resetting (bmiss 
count 4)
Mar  5 19:33:23 daedalus last message repeated 80 times
Mar  5 19:33:23 daedalus kernel: ath0: stuck beacon; resetting (bmkss 
ccunt 4e
Mar  5 19:33:23 daedalus kernel:
Mar  5 19:33:23 daedalus kernel: ath0: stuck beacon; resetting (bmiss 
count 4)
Mar  5 19:33:27 daedalus last message repeated 11 times


ath0_at_pci0:5:1:0:        class=0x020000 card=0x5a001385 chip=0x0013168c 
rev=0x01 hdr=0x00
    vendor     = 'Atheros Communications Inc.'
    device     = 'AR5212, AR5213 802.11a/b/g Wireless Adapter'
    class      = network
    subclass   = ethernet


wlan0: flags=8843<UP,BROADCAST,RUNNING,SIMPLEX,MULTICAST> metric 0 mtu 2290
        ether xxx
        inet xxx netmask 0xffffff00 broadcast xxx.255
        media: IEEE 802.11 Wireless Ethernet autoselect mode 11g <hostap>
        status: running
        ssid xxx channel 5 (2432 Mhz 11g) bssid xxx
        regdomain ETSI country XX ecm authmode WPA privacy MIXED deftxkey 2
        TKIP 2:128-bit txpower 30 scanvalid 60 pureg protmode CTS wme 
burst ff
        dturbo -apbridge dtimperiod 1 -dfs


After some time, the AP dies - my laptop scanning for an access point 
will no longer show on tcpdump -pntttiath0 (on the AP).

The system itself is still up, it's just that it's no longer possible to 
associate with the AP.
Rebooting makes the AP work again.


Suggestions?