Xerxes It definitely messed the sensitivity up. Not by means of affecting the base sensitivity, but rather the sensitivity changing to higher sens every now then for like 1/4 second then going back to normal. I had this issue in plutoniums Black Ops 2 also and that is the reason I don't play it.
I literally played MW3 just before the update came and everything was fine. But after downloading the update, all hell broke loose.
So the issue is that the sensitivity randomly changes or something happens that affects the sens for like 1/4 of a second. And that seriously fucks up my aiming. It's really noticeable. And actually, I thought that I have to give up this game also because it's actually unplayable.
I hope you can fix this soon. If you need help fixing this, you can contact me by email. I can take recording with OBS for you guys about the issue at hand.
Regards,
Defin