Hey, bear with me on this one!
Back when MW3 came out I got a hold of it a while after and tried to give multiplayer a go - it downloaded an update or two and i went in. Hit up multiplayer and it said I needed to be connected. This was odd, I thought I was. Pressed middle button and sure enough "connect to xbox live" was up. I pressed it and it failed, said I had to test connection. So I did and it sent me back to the dashboard. Upon getting to the dashboard Xbox live is fully functioning and I have 4 friends online! So back into MW3 I go and.... same thing. Even by the time the titles are up i am suddenly "no longer connected" (at no point did 'disconnected from xbox live' blip up). This was an isolated case and it was only MW3 so I ignored it.
Curious I try playing the game on my girlfriends gamertag and it works fine. (same xbox, tv, router, time of day, router settings, cable)
Then yesterday I am playing Trials Evo and I want to upload a track. I go to do it and it says i'm not connected to xbox live. Long story short the same thing now happens upon loading that game. I have played this game on everything I currently haves current settings many, many time with no problems. Suddenly today nothing. I decide to try Battlefield 3, another game I have played a lot over recent times, with no changes to anything and that too, as soon as its off the dashboard, i'm off Live.
I know there can be lots of router, ISP issues and things, but i've been happily playing for ages (aside from MW3) and its been fine. No settings on the router have changed, our package hasnt changed, no settings on the xbox have changed, the cable I use hasnt changed (even checked it for splits).
My Xbox Live is working, I am currently watching 24 on Netflix quite happily. If i were to now go and load up Battlefield 3 (for example) it would be gone as soon as. If i followed the test connection it would take me back to the dashboard where it would work again and I could straight back to Netflix and it would work.
Its driving me crazy, ive read countless threads and they all say about disconnects over time, or lag and the usual but ive yet to find anyone with this problem. If theres some so-simple-its-stupid fix out there id love to hear it. Thank you
(theres another issue associated with MW3 whereby my Gamertag WILL NOT record any achievements, or game progress within the game. To the point that I have to adjust the screen and brightness everytime i turn it on to find 0% progress on everything. Was saving that for relevent forum but mentioned it just incase it could be connected)