I don't know what the issue is. These files have the biggest mods to the game on the 360 I've ever seen. I mean they have even changes to the colours of the pitches, added different adboards around the pitch and such. They even made the rain heavier and added more stadiums. It could be something got to do with how modded it makes the game. I actually don't know really. Now, you shouldn't get banned because you have an unmodded console and copy of the game, but might get a bad courtesy rating online if you try to keep playing matches.
To get rid of it you need to go to where the game is stored and delete the edit, data pack, day one file i think its called and some others. Take a look at the names of the files on your usb on the xbox, theen you'll know which to delete on the xbox itself.
Try this file:
http://www.pesgaming.com/showthread.php?t=98583
It's a new version of a different file that wasn't working online either, but I've been told the new version works. you'll see 2 files here that are similar: LIGAS CON CANTICOS, LIGAS SIN CANTICOS. The first one is with chants the second is without. You only use one of either of these versions of files along with the rest.
EDIT: I think you may be right about the stadiums. Its the only thing that occurred to me, too.