Safari 5.1.2 can't connect to the server

Just a few days ago, my Safari 5.1.1 stopped loading pages, and I keep getting a "can't connect to server" error. Chrome and Firefox work just fine. My airport connection is clearly still working, and I can get mail as well. My family member's machine is running Safari with no issues.

I've tried reseting Safari, restarting my computer several times, and re-installing Safari, but nothing is working. The last thing I did the day before it happened was install Nik Color Efex pro 4, a Photoshop plugin, but that shouldn't affect anything. I installed it in the afternoon and Safari was running just fine the rest of the day. I also installed it on my family member's machine, and her Safari is still working perfectly.

I'm using the latest version of Snow Leopard (10.6.8) and am fully updated on everything else. I thought maybe the latest 5.1.2 would fix the issue, but it's still not loading pages. Any help would be greatly appreciated. Thank you.