Help Please Good connection but no windows mail or internet

my computer runs on Vista and i have BT broadband with the later black router. the connection (wireless) is excellent.
when i boot up all is fine internet (firefox) windows mail. then if i use any torrent programms, currently vuze, before that,unet
i then cannot receive emails or access the internet until i restart computer. i am using eset Smart Security and have tried disabling firewall and have checked settings in homehub everything seems ok but cannot stop this problem. any help gratefully welcome.