net question , plz plz help

Both yahoo & internet explorer,Google Chrome stop connecting to internet but firefox, google talk, skype connect ..., why?
suddenly
internet explorer stop open ant web page
yahoo messenger don`t login
but other net progs connect to net
like utorrent, internet download manager, firefox
i think it`s something wrong in my internet settings
some of my programs can send/receive information

i have no firewall
& windows firewall is turned off