For a couple weeks, most of the programs on my computer won't connect to the internet. The ones I know of that aren't working are Firefox, Internet Explorer, Opera, and iTunes. Programs that are working are Google Chrome, Windows Media Player, and FirstClass. I have Norton Internet Security, but it's off and I can't even open it. Windows Firewall is off too. Proxy servers are already disabled.
I've tried several different networks and a couple different routers. It's the same thing for all of them. I have another computer running Vista, and it's connected perfectly. My computer says it's connected, and it is, but it's just a few programs that aren't working. How do I fix this?