Odd network failure...

["Eric Brown" <ericbr2 gte net>]

I have my avanti running as a firewall/router (connecting the rest of my
network to my DSL line).  Recently, it has been silently dropping all
network connectivity to the outside world.  Nothing shows up in
/var/log/messages or /var/log/dhcpcd.log.  Manually restarting dhcpcd or the
ipchains script doesn't seem to restore connectivity; only a reboot will do.
Any ideas what might be causing this?

I'm running:  RedHat 5.2 with Linux kernel 2.2.12, dhcp client daemon 1.3.

Thanks,
Eric