bridging... stops?

[Val P]

Hi,

Every now and then (maybe once a month), our freebsd firewall/bridge 
stops bridging. There are no errors anywhere, and no obvious triggers 
(for example, it was working sunday night, Monday morning it was dead).

Turning off IPF or setting its rules to pass all did not fix the problem, 
so I am somewhat ruling out IPF as the problem. Rebooting the machine did 
fix the problem -- everything was working once again... but I'd rather not 
be fixing problems the microsoft way. :)

How can I go about debugging this issue when it happens again?

FYI: Proliant DL380/G2 (or G3, I forget?) with 1GB RAM. Three active NICs: 
copper broadcomm gigabit on bge0 (management port), and fiber broadcom 
gigabit on bge 2/3 (bridge endpoints). Single processor at around 2 GHz 
or so. Load on the server is light, no packet loss. Running FreeBSD 4.8. 
There were absolutely no changes (physical or software) between the time 
the machine was working and the time it stopped working. Whether or not 
there were any transient network conditions I do not know. I did find a 
machine on the network which was broadcasting with an IP of 127.0.0.1, 
and killed it.. but that was after rebooting the server and restoring 
bridging functionality.