Whenever I sign on to Xbox live for the 360, i get disconnected from it about 15-20 minutes into the session. I've been having problems with PC-based online games as well, where my internet connection would disconnect me from a game after the same amount of time. I have no problems surfing the internet for however long I want, and there are no other problems with my internet connection. If there's any known solution to this problem, please let me know!