NOD32 is apparently reporting iw3sp.exe (the COD4 executable) as malicious which is not really true. To solve this: Go to AMON, Click Setup, Go to the Exclusions tab. Add the entire Steam folder, or at least your account name within steam/steamapps. That should fix it. Or just change to a better Virus scanner

This will turn off the active scanning for whichever folder you choose to exclude.

Thanks to hwkiller from the Steampowered forums!

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