Firefox tells me that they cannot find server at any site I try. I have no problem with e-mail or with internet explorer so I am connected to internet but firefox does not recognize any site. I think it is blocked but do not know how to unblock it.

I am using Firefox version 3.6.2 (Idid not like ver5) and everything has been working fine. All of a sudden I cannot reach any site with Firefox (it tells me it cannot find server at every site I try). My e-mail works fine so I am connected to internet. I am using Internet explorer to access this site now but I want Firefox back. I think I may have accidentally blocked it but I do not know how to unblock it. Any help would be greatly appreciated. I do have McAFee installed and I think it blocked Firefox but i can't find any to unblock sites. Thanks my system is a Dell studio running Vista Home premium