Well here's what I did: since I was still convinced it had to do with the built-in firewall, I opened the extensions folder, picked up the ipfirewall.kext and threw it on my desktop. Then I restarted. And whadd-a-ya-know, it worked, but when I tried to but it back, it said a newer file named ipfirewall.kext is already there, anybody wanna fill me in about what just happened?