Again, sorry guys, but I've discovered the root cause of my particular problem. it is an internet filter.
I go to college and I'm trying to use my xbox on campus internet. The campus has a MAC authorization system so that each MAC address (hence each computer) must log in via an HTML log-in page and it stays authenticated for a few weeks until one must authenticate again.
In order to get around this I spoofed the MAC address on my desktop (a mac mini, so rather easy with terminal), logged into the campus internet connection, then reverted my MAC address on my desktop to its original and logged in again.
On the xbox you can specify an alternate MAC address, I simply set this to the spoofed address I mentioned earlier. This seemed to work for a few days, and then the problem I mentioned in the previous posts began to happen. I'm guessing the filter caught on to my shenanigans.
To check this, I connected my desktop to my phone's internet via wifi tethering and shared the connection with my xbox via ethernet. Lo and behold, the errors are gone, and Live works perfectly again.
I know this doesn't necessarily help any of you other guys, but It may be a start.