Most ISP's have a link on somewhere on thier site, ususally under support, that gives the "current network" or "current system status"
If you are on BT Yahoo Broadband - i'm guessing from what you said. Then :
http://help.btinternet.com/yahoo/hel...Y_Home,00.html
SHould take you straight to the service status page - assuming of course that the problem they have lets you connect!
Memetic.