I've been having this problem for a few weeks. When I sign in, my gamerscore says 0, shows no achievements, and my avatar is gone. I can still play any game (but I don't earn achievements), and talk in parties and stuff. The only fix I have found is to load GOW3, then once I am into the game sign out then back in. This is the only way things go back to normal, but it is a total pain! I just want everything to be set my MW3 time.
I currently have my gammertag on a flash drive. I have 2 slim consoles. One is about a year old, the other one a month. I have used both wired and wireless connections, and have had the same problem on both consoles (which are on different networks in different locations)
Has this ever happened to anyone?!?!?