Do you have WOW ultra?
If so, do you have multiple Xbox's (or Ps3's) connected at the same time?
I just called WOW because when I turn my 360 on it kicks my son off. vise versa. We can't log in for like hours. WOW rep said that it's the gateway/modem that's causing it. There is no fix any time soon and it's the way the modem is designed (they put it in bridge mode?).
I then asked if I could turn off every function on the mode (firewall, all the other crap) and just hook up my own router.. She said no it wouldn't work. The wireless on this box sucks as it is for being a wireless N router (disconnects frequently).
Anyone having this issue? If so I'll probably end up dropping WOW.