For added security my router (Netgear DG834G) allows me to restrict which devices can access my wireless network, based on their MAC address. When enabled, I can't connect to Xbox Live - on the test on the 360 it fails at "Wireless Network". All my other devices are fine (2 XP PC's, 1 Vista PC, 1 PSP and 2 DS's). I've checked and double checked that I have my 360 wireless adapter's MAC address entered correctly. When disabled, the 360 connects fine. Anyone else suffer this?