Dude I have exactly the same problem, downloaded Day Z yesterday and the mouse acceleration problems are literally intolerable, I've been looking everywhere to try and find a way to fix this. It literally feels like I'm controlling my character with a joystick and a rubber band, every time I need to move I tug on the rubber band and I swing somewhere towards where I was intending. I can't find anywhere that has a fix for it. I've tried changing mouse smooth. I've tried changing: From Default 1000 and 3 to GPU_MaxFramesAhead=1;GPU_DetectedFramesAhead=1; I've tried editing all graphics in every kind of way... and still nothing. Oh and I have a Microsoft mouse not Logitek or whatever the other guy had so it's clearly not the mouse. @ ZedsDeadBaby you have no idea what you're talking about. Watching this video as an example: http://www.youtube.com/watch?v=APdlpgsBqJ8 makes me so jealous. The fact that in the first minute he's able to aim at the door, then at the person, then at the door again in one go is exactly WHAT I cannot do. The mouse movement just flies everywhere. I haven't attempted using a gun yet, but when I fight a zombie... it takes like 5-6 mouse swings in a short space to actually aim at them. It needs to be fixed :) I hope they do it soon.