Only Internet Explorer works

Ok im having this really annoying problem. I can only connect to the internet with Internet Explorer i can use Limewire too. I have a zune and it wont let me connect to the marketplace and i cant use firefox or Google Earth either. im also not able to use Bit Torrent. I have Checked my firewall settings and it still didnt work. My computer is virus and spyware free, i have allso used winsockfix to restore my rgistry keys. can anybody help me?