Plutonium

I had the same issue. I found out the downloads were getting split between the plutonium folder and an actual Activion CodWaW folder. So go through %appdata%/local/Activision/CoDWaW and drag the mods folder into %appdata%/local/Plutonium/t4/storage. It will merge all the existing folders and recombine the mod files as they are meant to be. It should play normally after this