Internet connection blinking on and off

[D1sc1pl3 0f Mal1c3]

The intenet connection on my PC keeps blinking in and out, and it's playing hell with my my games and is really annoying. It drops me out of WoW every time and does the same with Source or it freezes for a few seconds then comes back. On the desktop, it will pop up the little message that says that a network cable has been unplugged and is immidiately followed by my signal coming back again. It works fine at my friends house, however. I'm not sure if it's a connection issue or a router issue. Any ideas?