Windows 7: What would cause...

Me to suddenly be unable to navigate to a public site like emsisoft.com. On a clean install there's no problem, but recently I've been denied with a popup suggesting that if I'm behind a firewall, "make sure Firefox or IE is allowed to access the internet". I've changed no settings, I've thoroughly scanned for malware and viruses, and removed everything, but the problem persists.

Hi there!

What Firewall software are you using? Have you tried to add Firefox to exception list? Does it happen with IE or other browser?

Just the firewall native with Windows 7. It happens with both browsers. I haven't added Firefox to any exceptions list because it works fine for everything else.

What did you use to scan with and what was removed?

Can you check the LAN Settings and make sure it's set to ""Automatically detect settings"

Tools > Internet Options > Connections > LAN Settings

I have, and it is.

I use Emsisoft Emergency ToolKit for malware, along with Endpoint and AVG for virus.

Check the Host file. Go to C:\Windows\System32\Drivers\etc and see if there is any unwanted entries.

Also run this tool SF IE Restorator - Troubleshooting General Issues with IE

The Host file appeared normal. I'll have to wait until I get to my home machines to try your tool. I'm forced to use XP at the office.

It's kinda strange that I can run Firefox or Explorer in SandBoxie and there's no problem going anywhere.

try this: Check your proxy settings, No Proxy, restart browser
edit: or for IE, tools ==> internet options ==> advanced tab - Reset