Problem with internet browsers

So randomly yesterday, Firefox suddenly lost its ability to access the internet.
I checked the connection settings, they were all in place. I checked Windows Firewall, and Firefox was still on the exceptions list. To be certain, I deleted and re-added it. It continued not working.
I reinstalled the program. It didn't work.
I downloaded and installed an earlier version. Didn't work.

Internet Explorer worked, obviously.

I decided to try an experiment.

I downloaded and installed Opera. It couldn't access the internet, either. 
I checked the connection settings, they were all in place. I checked Windows Firewall, and Opera was alreadyl on the exceptions list. To be certain, I deleted and re-added it. It continued not working.
I reinstalled the program. It didn't work.

Today, in Firefox, I went to about:config and disabled IPv6, as suggested by Mozilla themselves.
Didn't work.

Soooooooooo...
Is there anything I could possibly be overlooking which would disallow all browsers other than IE to access the internet?

What OS are you using? Either way that's a wierd error.

XP.

Hmm.. Windows Firewall is an utter piece of shit. My suggestions is go grab Comodo Firewall Pro and allow Firefox and Opera. Comodo solved my connection problems.

Use Safari ?_?


This is more likely than not a problem with your actual internet, not the browser.