I had a problem somewhat like this a while ago, I called xbox live service and they didn't do sh*t. So after all else failed I formatted my harddrive and everything was fine (besides the fact I had to download everything again).

Before you get desperate and decide to format your hdd, your problem could be a corrupted cache, which is basically where all the updates are kept. To clear it go here.

EDIT: nvm, I was at a LAN party the past 2 days and never got online, so yeah I guess it's the fall updates. XD