Plutonium

Same here. The plutonium IW5 window crashes when trying to apply the settings and seemingly hijacks the mouse input. Keyboard input still works so I just alt f4'd the console to kill it. I edited the plutonium.cfg config file in C:\Program Files (x86)\Steam\steamapps\common\Call of Duty Modern Warfare 3\players2 and set the line with r_displayRefresh to seta r_displayRefresh "144 Hz" instead, that seems to work.