And did you scan for the malware with Grif's advice?
That's not enough clues to write do this, but a clue it's time to try the reset defaults and scan.
I am running Windows 7 64bit and both Windows IE and Firefox will not load any webpage. I get a message similar to "IE cannot connect to the server" and comparable for Firefox. Chrome works fine. I downloaded and installed Safari and it will not work either. The same reason. I make sure both are approved for the firewall and had done a delete and reinstall of the browsers.
I figure it must be a setting someplace but cannot figure out where.