GHOSTIN_MONSTA in the meantime you might be able to play offline following some instructions
Save the content below in a .bat file that you save in %localappdata%\Plutonium then try running it by double clicking it with the launcher closed
@echo off .\bin\plutonium-bootstrapper-win32.exe iw5mp "E:\Games\Others\Call of Duty Modern Warfare 3" +name "John Smith" -lan