So, I was playing on my 360 yesterday. Everything works fine.
Today, I turned it on and it was super slow - you know that little white line going around in a circle on a coloured background? Well, that was super long.
Then, I tried to connect to the internet. It wouldn't let me sign in on live. I went to Wired Connection (System settings place), and tested it. It said everything was up. I'm even port forwarding my Xbox, and it has worked all the time.