Internet connection problem

I can?t connect to internet with any program, my connection is alright, but something blocks me from connecting to servers. I had this problem earlier, none of my programs could connect, only skype. In that time I tried many things, but only re-installation of windows helped me. Now I?ve got same problem, but now even skype isn?t working. I shuted down my firewall (zone alarm) because it allowed me to connect to internet earlier, but when I restart my computer, it won?t help me too. It looks like some virus that attacks firewall, blocks my connection, waiting for me to switch my firewall off so then it can access my pc and cut me from internet completely.
Please help me solve this problem, I don?t want to re-install my windows again.