MW3 XP LOBBY

Okay so I've been able to get into xp lobbies recently, however I have a problem. When in low scoring lobbies (e.g 23000 per kill) they let me play, however when it comes to high scoring lobbies (e.g 1000000 per kill) they kick me out and say "Network Connection Lost" as soon as I am about to kill someone?

Can someone help me, is there anyway to solve this problem? thanks.

how would u connect to a xp lobby??????