I nearly had all the achievements for this game.
The one I never managed was Blue Ribbon (Complete a 4-player Competitive Co-Op match in 1st place over Xbox LIVE. (Online co-op only)), due to not en ...

yesir

But how can we do it ?
I'm sorry i don't know a single thing about WaW modding/infections, and i kinda need my last 2 bugged achievements to be unlocked...