Forge/wargames/custom games not working

Okay, so the very first thing I did was install disk 2. After playing Halo 4 Campaign to a certain point before I needed to go to bed, I went to try out forge mode. The maps were loading SUPER SLOW. When the loading was complete, I went to launch, everything somewhat normal-ish at this point. The loading screen comes up THEN… I’m kicked to the main menu of the game. What?

Try again… Same thing.

Okay, well, this is inconvenient. Let’s try infinity slayer.

Sweet! Played a match, did pretty well. Next game starts… kicked back to main menu.

I’ve uninstalled and re-installed 3 times and it still hasn’t worked. I tried to install from xbox live earlier, but it said “can not download” after it reached 100%. looked like a server problem, so I’m trying again right now. (23% as I am typing this)

Anyone else have this problem? have you resolved it?