I've been conducting a test.
Since I've blocked P2P traffic (edonkey, bittorrent and gnutella), my internet
(nat) firewall has been up for a few months now.
Yesterday, I've installed mldonkey on a machine to test whether or not it would
affect the firewall. Sure enough, when mldonkey had been up for an hour, the
firewall crashed again.
The mldonkey client was installed on a linuxbox in the dmz (routed dmz, no
portforwarding, nat or proxy arp). So this should rule out any nat related issues.
I'm now convinced it's the traffic. It couldn't be the networkload, because the
P2P client was configured to use 1 kb up and down on a 6 mbit internet connection.
I can't wait for the freebsd 6 version of m0n0wall.