I have ubuntu 12.10 (downgraded from 13.04 when I faced this issue). I am a newbee and don't know much of technical side like commandline on the terminal. I have a wired internet connection and it was working just fine for last few months since I installed ubuntu. my OS got upgraded to 13.04 and it was still fine. Since last 3 days, network shows connected, connection stays for few seconds and then websites stop loading. Connection shows as connected, but pages don't load. I have to reconnect again to access a website and the connection goes off again in say about 10 to 15 seconds. So I use my internet by connecting and disconnecting every few seconds.