if you are in UK on virgin, they are having ALOT of problems at the minute and it is weird, i can for example always get onto steam and talk to my friends on it, 90% of the time get onto teamspeak but hardly ever get onto online games at the minute and after about 7:30pm it is lost completely, so it may not be your system, just virgin.
If you aren't on Virgin or not even in the UK then check firewall settings.
Have you tried going to different pages? If you only rely on your home page to tell you then the site may be down. Try going to another site and if that works then you know that it isn't you, it is your home page provider