Quoted from DICE. Hi all. We just wanted to give you a short update on our anti-cheat measures and how we think about a couple of aspects regarding this in Battlefield 3. As you know, we are always striving to keep Battlefield 3 as fair as possible of a game. This takes many shapes and forms, including (but not limited to): Reading the reports that you file; Analyzing player behavior and stats to catch potential cheaters; And hiring more people with the full-time job of increasing our anti-cheat measures and decreasing our response times. To make sure that everyone on the Battlefield plays multiplayer on equal terms, we also want to make sure that the game files have not been compromised for any reason. For us, a changed game file indicates the user is trying to affect the game to get the upper hand in multiplayer, whether that’s by modifying the graphics or making the game otherwise behave in a manner that is not as designed. We will not differentiate between someone who has modified the game for reasons he thinks are benign and a player doing it to cause grief online. Players tampering with the game files for any reason need to know that this is against DICE and EA policy and is grounds for banning. Everyone else just needs to know that we will always strive to create a fair online gaming environment.
I think what this really stems from is the game modifier pack that has been floating around the net. It allows people to change various aspects of how the game works. This is why you've seen some recent videos with different vehicle camera angles, different game coloring, physics effects, etc. The primary response, I personally believe is due to people being unhappy with the blue tint and using this game modifier to remove that tint. Some people have been banned for it and are feuding with DICE.
