so just tried going onto multiplayer and it came up with this '' communication with the xbox live servers has been intertupted'' can any1 help !

It sounds like your xbox has possibly lost its internet connection to the internet, I myself have never seen this error.

Just had a read on google, it states "I believe there is a tempaban on those who quit games early and hence can't get into any online matches, nothing to do with the servers that are running fine, I tried this with both Xbox live accounts I have, one I quitted several matches before completion, the other I started from scratch and works fine to prove is nothing to do with the connection, either yours or MW3s, rather a "secretive" way to ban those who annoy others."

Anyway, hope you find your problem.

Mw3 has so many problems!

this happened to me a lot of times, especially when i had some intermittent connection issues.
i'm not sure though if this is also a mw3 server problem but i noticed it several times during bad connection times only. now it's gone.