Cisco :: 4402 Light Weight APs Drop Out After Land Attack

We have a WLAN consisting of a WLC 4402 and 11 lightweight APs. For security/compliance reasons we have a Cisco PIX firewall that sits between the WLC (outside) and the APs (inside). The APs are allowed to form LWAPP tunnels through the firewall (inside access-list) to the WLC and the WLAN works as expected.The firewall then limits traffic from the WLAN (outside access list) to certain the internal systems.I have noticed that every so often the firewall logs show continuous "Land attack from 0.0.0.0 0.0.0.0" messages then all APs are disconnected (all lights flash).