if im playing online multiplayer such as call of duty, i can play for days without ever getting kicked off. However if i try to listen to last.fm, or talk to my friends when im on the dashboard, or even in singleplayer, i am usually kicked off xbox live within five minutes. Iv tried restarting xbox, restoring network settings to factory defaults, redownloading profile, and restarting internet router. I run off a wired connection, and it happens even if my xbox is the only thing connected to the internet. It usually wil not let me sign back in unless i test xbox live connection.