ath problem

Hello,
I'm unable to get a wireless access point to work properly and for the 
life of me I can't work out why. I've spent the past few evenings 
trawling the mailing list archives without much success. I'm hoping 
someone can point me in the right direction.
It's an Atheros 5212 (Wistron cm9 miniPCI) in a soekris 4801 box.
A test client (WinXP SP2) can associate and on occasion obtains an 
address from the DHCP server on the ether side of the AP. Most of the 
time it is unable to obtain an address however, and even when it does 
after a few seconds it changes to the default not connected address of 
the 169.254/16 network.
Initially I was trying to configure hostap for wpa+802.1x (EAP_TLS), the 
802.1x worked fine and the XP laptop received its address, again after a 
few seconds the address would revert to the 169.254/16 network. To try 
and identify the issue I switched to a simple wep mode (without hostap), 
but I have the same issue. The athstats tool reports a lot of failures.
I haven't attached pages and pages of debug output as I'm not sure what 
would be required and don't want to flood the list. I have just attached 
a few of the basic things, but if more information is required I can 
obviously supply it.
Thanks for your time
andy
btw - the same laptop works perfectly with an identical config (except 
the SSID is different) on second 'off the shelf' AP.

ap# ifconfig ath0
ath0: flags=8847<UP,BROADCAST,DEBUG,RUNNING,SIMPLEX,MULTICAST> mtu 1500
        inet6 fe80::20b:6bff:fe35:cb82%ath0 prefixlen 64 scopeid 0x4
        inet 0.0.0.0 netmask 0xff000000 broadcast 0.255.255.255
        ether 00:0b:6b:35:cb:82
        media: IEEE 802.11 Wireless Ethernet autoselect mode 11g <hostap>
        status: associated
        ssid Z channel 9 bssid 00:0b:6b:35:cb:82
        authmode OPEN privacy ON deftxkey 1 wepkey 1:104-bit txpowmax 53
        protmode CTS dtimperiod 1 bintval 100

ap# sysctl net.link.ether.bridge
net.link.ether.bridge_cfg: "ath0,sis0"
net.link.ether.bridge_ipfw: 0
net.link.ether.bridge_ipf: 0
net.link.ether.bridge.config: "ath0,sis0"
net.link.ether.bridge.enable: 1
net.link.ether.bridge.predict: 0
net.link.ether.bridge.dropped: 0
net.link.ether.bridge.packets: 0
net.link.ether.bridge.ipfw_collisions: 0
net.link.ether.bridge.ipfw_drop: 0
net.link.ether.bridge.copy: 0
net.link.ether.bridge.ipfw: 0
net.link.ether.bridge.ipf: 0
net.link.ether.bridge.debug: 2
net.link.ether.bridge.version: 031224

ap# ./athstats
1666 tx management frames
5 tx frames discarded prior to association
996 tx failed 'cuz too many retries
11502 long on-chip tx retries
221 tx frames with no ack marked
204 tx frames with short preamble
57002 rx failed 'cuz of bad CRC
136258 rx failed 'cuz of PHY err
    122418 OFDM timing
    13840 CCK timing
28961 beacons transmitted
165 periodic calibrations
4 rfgain value change
4489 rate control checks
5 rate control dropped xmit rate
rssi of last ack: 19
avg recv rssi: 33
59 switched default/rx antenna
Antenna profile:
[1] tx      472 rx     3037
[2] tx      414 rx       29

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