MadWiFi issues after being connected for some hours

Hi everybody,

I'm using an old Centos 4.1 box (kernel 2.6.9-22.0.1.EL, Pentium III 550 
MHz, something which dates around y2k, or maybe even before) as a 
gateway/firewall at home. It is not connected to keyboard, mouse and 
monitor, I have plugged in an ethernet NIC (RTL 8139 chipset) and a 
D-Link GWL-D510 wireless NIC using the Atheros chip AR5212, which are 
used by external clients to connect to the box or just to use it as a 
gateway, while the NIC present on the motherboard is connected to an 
ADSL router. I started using madwifi-ng-r1611-20060528 and with this 
version of the driver the machine used to freeze completely after some 
hours during which the wireless NIC worked perfectly (I can even use the 
virtual AP facility, which is really nice), becoming unresponsive to 
ping both on the wireless and the ethernet NICs. Then I read on some 
forum that someone else was experiencing this problem with madwifi-ng 
drivers, so I moved to the stable MadWiFi release 0.9.0 downloaded by 
SourceForge.net, which was claimed to work properly. Unfortunately the 
problem has not really gone away: now the machine doesn't freeze anymore 
and the system has become absolutely stable, but all the same after some 
hours whe wireless NIC is up and able to receive incoming connections by 
clients, it suddenly becomes unreachable, and even connecting to the box 
by from an external client through the ethernet NIC the Internet is not 
reachable, as if there were a routing problem, while logging into the 
box via SSH through the ethernet NIC it is still possible to access the 
net normally. It all sounds like kernel issues caused by the driver, 
which stops working and screws up routing, even thoughe /sbin/route 
keeps reporting the correct routing tables. When the system is in this 
state, restarting the wireless NIC with these commands:

wlanconfig ath0 destroy