I too have experienced the freezing, after 8-12 days it would freeze. I
didn't notice it until I upgraded the system to 1.21 from 1.2, although
I don't think the freezing started right after that so I don't think it
is version specific, it just didn't happen in 1.2 if I recall correctly.
I have rebuilt the ruleset and config from scratch numerous times and it
didnt help. The only other thing that I changed before the freezing
started was I added in traffic shaping, but as it has been discovered
that the m0n0 boxes will still sometimes freeze without traffic shaping,
that doesn't seem to be the problem. I currently have migrated back to
1.2 and have older images as well. I'm going to keep going back as it
continues to lock up. My m0n0 has been up for about 7 days and 8 hours
now. My max uptime previously has been 33 days but that isn't accurate
of how long the box could run as I had some internet connectivity issues
with the local telco and was forced to reboot my router tons of times
for no reason. ;-)
 
Before I moved into my new house, my m0n0 box had been up for at least
200-250 days or so. It just sat in the corner and did it's thing. I did
swap out a network card for an intel unit after I moved so I could do
vlans and optional interfaces over one card. Perhaps vlans and optional
interfaces on intel cards has something to do with it.
 
Andrew