Recently I've noticed many guys have pb problems and many of them don't know how to solve them. Last night my buddy couldn't connect due to some problem related to service restrictions and sometimes there's a message "server disconnect". In many cases you need to update punk buster or delete complete pb folder and reinstall, or in the worst case scenario ask somebody to give you theirs pb folder. You may also be banned so check with admins if they've banned you. Also windows firewall could block pb service so turn it off.