@cmb:
If something went really crazy requesting BOOTP or DHCP leases, it could create a really large DHCP leases file, which could exhaust the space in /var/. Can't recall hearing of that happening with IPv4 but it's possible.
No printers on the network, just a couple Win7 boxes, and an ARM box running a linux variant at the time.
I'm in the process of getting more data logging setup so if it occurs again I might be able to provide more info, but one thing I saw in pfsense was alot of references to nics changing from their ip address to 0.0.0.0.