You can't ping a smoothwalll, but it is accessible from https on a working machine.
I have logged on to the firewall locally and pinged back to my troubled maching, the the arp record is there as well.
I've even ran tcpdump on each of the firewalls nic's and packets do come back. They very hard to read, even though they look ok, but I may be missing something. I'll have a look at the smoothwall recomendations on proxy's, but I have three other OS installs working without it.
Have any good fossicking around there? I enjoy stirring in the dirt a bit around here, but I don't find much.