Self-Suffocation on Soekris - why?

Hello,

I've been seeing this for a loong time, and on a number of the latest
versions. Finally, I could get some info from status.php before I was
totally out:
After some 10 to 15 days each, my Soekris-Box running m0n0wall stops
incoming WiFi-connections, drops the existing ones and refuses to dish out
new ones to any client. Only a reboot gets the system back to normal.
Finally, today I was able to intercept this state just before it went out
100 percent. The log shows continuous re-authentications, while the ping to
the box gets very lagging and dysfunctional:
$ ping 192.168.116.200
PING 192.168.116.200 (192.168.116.200) 56(84) bytes of data.
64 bytes from 192.168.116.200: icmp_req=2 ttl=64 time=312 ms
64 bytes from 192.168.116.200: icmp_req=3 ttl=64 time=72.8 ms
64 bytes from 192.168.116.200: icmp_req=6 ttl=64 time=14.8 ms
64 bytes from 192.168.116.200: icmp_req=7 ttl=64 time=205 ms
64 bytes from 192.168.116.200: icmp_req=8 ttl=64 time=619 ms

Can someone point out to me, please, what is going on, why, and how to
eventually prevent this resource exhaustion from happening?

Thanks in advance,

Uwe

Since ezmlm didn't want to accept my shortened and compressed status info
(21.2 k), I put the uncompressed version with a lot of the active sessions
removed here:
http://www.uni-due.de/~adc019s/monowall_probs.status