well just to add. i have a modded xbox with an X2 chip in it. I play on both live and on Xlink Kai. I also have SW:BF, which i have played on both Kai and XBL, however i just mainly played on XBL. Now when i played on Kai, my mod chip is off, as well on XBL(of course). I hate cheaters in games and im not one of those - so if MS is just removing hacks fine...but otherwise its crap.
Now i also have ESPN NFL 2k5, and NHL2k5, both of which i have played on XBL, no problems - MOD OFF. I also have one of the other so called problem games Madden 2005, which i have played with mod on.
Anytime i run a backup i have the MOD on (obvious) but whenever i run a retail i have the MOD off( not matter what im playing XBL or XLink)
I've havent been banned at all - and shouldnt be because i havent violated any rules.
I think its a bit more involved than games causing problems. Also i tried the password trick as of late, and then powered up the SW:BF game and it never tried to sign me in before the game started. I always have to do that myself.
On a side note, i have noticed 1 time when i updated a game on XBL, it changed my autosign in to enabled. have no idea why that happend. but i caught the change and switched it back. So anytime you get an XBL update ALWAYS check to make sure your sign in is still disabled.