If ISP's might be the problem, Im with Bigpond and theyve been abhorent when it comes to xbox live. For me it was mostly an issue with the garbage Tohmson router they INSIST our house uses. They fooled my dad into thinking he had to buy their one because our other router was incompatible with their service. BULLSHIT, any router will work with any ISP. These routers seem to be a common issue in Australia, they're so locked down that you can barely port forward, and when you do, your still behind NAT, so its essentially port forwarding dosnt work.
The routers also 'forget' the physical adress of your connected devices, so it wont recognise which device is which after a little while. On top of that, if you reset to factory settings, they wont clear the old configuration properly so that causes 'random' issues. Then sometimes the routers reset randomly anyway.
Fixed my issues by assigning a static ip to ever device in the house, rebooting everything as i went, then gave my Xbox a dynamic IP and DMZ privilages. If all my other devices arent on static, putting the Xbox in DMZ IS A LIE, its still behind NAT.
Just if anyone is having those problems. If you call bigpond they'll tell you port forwarding is a skill that you couldnt possibly have and youll need to pay for a tecnitian to come out and do it for you. They also told me that they dont support online gameing. Odd, all their adds boast how good they are for multiplayer titles,
Also there was some kerfuffle about people getting free MS points, might be something to do with that, or...LULSEC, (oh but I jest)
Oh I can't sign into the website either.
