OK, here's another example.
X-ecuter 1.0, MS Dash with Live Beta installed. No other mods except probable still have a renamed dash or 2 unsused on the C: drive. No games or other HD hacks.
All was fine till sometime last weekend (Discovered problem on evening of 11/11/2002, USA EST).
Even system live settings menu with no disk installed won't connect...ie...XBox Live Not Found.
Tried IP Address change...no-go.
Kicker is...I was one of the saps that honored a MS request on the beta forums to leave your xbox connected to live after playing for network tuning! This may explain why some can still connect....cause MS can only find you when your not playing?

Open to suggestions to test...but don't have equipment to try eeprom serial change. I do have switch in hand to install when I get home.
Cheers