Does other program that work trough the internet works fine?
have you tried other programs that work with the internet and
see if they work Ok ? (Email, P2P, online poker, games He He He)...
maybe you should check you internet connection settings, maybe there is proxy setting that you
sould disable or some fixed ip that was set and you should switch to automatic?
open your internet excplorer -> Tools menu -> Internet options :
Select connections -> Lan Settings -> See that the only top check box is checked.