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Rebooting Modem
"Games for Windows – Live reboots my modem. My modem (a Linksys WCG200 recommend by Comcast) reboots periodically when trying to connect or after connecting to GFW – Live. It took me two hours to download my XBOX Live profile to my computer. Why? Because my modem would reset over and over. This bug was reported during the GFW – Live beta. It happens in Bug Bash and HALO 2 (PC), both using GFW – Live. So, it only happens when GFW – Live is being used."
I have the same problem when using BitTorrent or anything that causes you to start streaming "up" a decent amount.
Not that that's the problem for sure, but it may be. I find that my connection drops and i have to release/renew the IP on my modem. From the research i've done, it seems that many ISPs have a cap on your upstream communication, and if you exceed it (or continually reach a certain limit) your connection gets bumped.
I was fine for a while using BitTorrent, but after a few weeks i started getting bumped all the time. I've dropped my upload speed and haven't had that issue since.
Maybe GFW-L is streaming too much data up and your ISP thinks you're "acting as a server" and bumping you.
Just a thought anyways :-)
XT