I know it's something on this end. It's obviously something within this particular PC. Like I said, my other PC's behind the same router work fine. That 127.0.0.1 error caught my attention as well, but I don't know what it means. Isn't that referencing the PC's own loopback? I know my router's address is 192.168.1.1.
I wasn't aware that browsers should ever be trying to connect to the loopback unless maybe you were running a local proxy/filter of some kind, which I'm not. I've also double checked that all proxy settings are clear.