"Verifying Selection" in custom games. Help.

Lately, whenever I try to select a Game Type or a Map in a custom lobby, I get an extended “Verifying Selection” load screen followed by a prompt informing me that "The name for this map variant cannot be displayed online. It will be replaced with BLAM! when playing on Xbox LIVE.

Afterwards, my Network will often times automatically switch to “My Xbox 360” and I will be disconnected from my current party and be unable to see my friends list or join anyone else’s games or parties. Also, I am unable to switch my Network back to “Xbox Live” and must sign out and sign back in, in which time I am reconnected to the party I was in.

I know the game types are fine because I’ve used them all multiple times without incidence and a great deal of other players use them, too (like v4 Dispatch for example.)

This just started occurring recently and I have no idea how to fix it. Please Let me know if anyone has found a way to fix this.